Are you a parent of a promising up-and-coming athlete who is able to hang with his peers in multiple sports? Tell that youngster to keep his head out of the books and instead hit up the weight room and the practice fields seven days a week. Professional sports are, until further notice, about far more than just teamwork and attempting to win championships that will forever have athletes mentioned with all-time greats that came before them. Billionaire owners of clubs and of franchises who are desperate to win titles pay literally millions upon millions of dollars to athletes every year.

Those player salaries alone allow athletes to live beyond comfortable existences long after they have called time on their careers. That amount of wealth does not even include the numerous endorsement deals that are awarded to athletes who excel at sports and also happen to be good looking and well-spoken in front of microphones and cameras. The likes of Cristiano Ronaldo, Lionel Messi, LeBron James and Kobe Bryant are international superstars because of advertising campaigns that have featured those men along with those individuals being four of the best athletes to ever play in their sports.

A wide variety of sports are represented in the top-20 of the highest-paid athletes of 2015 as released by Forbes in June of this year. That includes some of the biggest single names of the National Basketball Association, National Football League players who have managed to cash-in on massive contracts, and also world football stars who would fetch over $100 million dollars on the transfer market were they to be sold this coming summer. Last but certainly not least is a pair of boxers who laughed all the way to the bank after disappointing fans with one of the more boring main event fights you will ever behold.

20 20. Derrick Rose: $33.9 million total earnings

Nobody should be feeling too sorry for Derrick Rose these days. He is a very wealthy man thanks to money paid to him by the Chicago Bulls and also endorsement deals that he has signed over the years. With that said, Rose may never meet the high expectations many had for him at the start of his NBA career due to suffering multiple knee injuries. Add in the fact that Rose and the Bulls have yet to find a way to down LeBron James in the postseason, regardless of if James has been playing for the Cleveland Cavaliers and Miami Heat, and it is easy to understand how Rose could find himself frustrated even while looking at his bank accounts.

19 19. Jon Lester: $34.1 million

It does not matter where you are from or your background: Teach your children to be baseball players if they are great athletes when in their early years. The two-time World Series champion as a member of the Boston Red Sox fetched a six-year deal from the Chicago Cubs this past Major League Baseball offseason. He earned $30 million off of a signing bonus and the 31-year old could make over $150 million total off of that one deal. Lester is currently set to be a member of the Cubs up through the 2021 regular season, after which he can happily ride off into the sunset.

18 18. Gareth Bale: $35 million

It was in the summer of 2013 when Gareth Bale called his switch from Tottenham Hotspur to Spanish giants Real Madrid his “dream” move. A dream it was in season one, as Bale netted game-winners in the Copa del Rey and Champions League Finals for his new club. Dreams can become nightmares in an instant, however, and that was the case for Bale in 2014-15. His production slowed to the point that home crowds booed the Welsh wonder during La Liga contests, and there have been some whispers that Real would be willing to listen to offers for Bale's services this summer.

17 17. Fernando Alonso: $35.5 million

The first member of the racing world to make this list, Fernando Alonso is an accomplished driver and a double world champion who has recently been in the news for items other than successes that he has achieved during his career. Alonso exchanged Ferrari for McLaren earlier in 2015, a move that has been criticized by racing journalists. There has been speculation that the 33-year old, who has been unable to keep up with the likes of Lewis Hamilton and others, could consider making a move from Formula One sooner rather than later. Has his time to win a third championship already disappeared?

16 16. Ndamukong Suh: $38.6 million

Conventional wisdom suggests that NFL teams may regret paying such a massive salary to a defensive player, especially one who has a history of getting in trouble on the field as did Ndamukong Suh during his time with the Detroit Lions. The Miami Dolphins nevertheless gave Suh the contract desired by his camp, awarding the top defensive tackle in the game today a contract worth nearly $60 million guaranteed. Suh could potentially make over $100 million as a member of the Dolphins, so long as he abides by NFL rules and puts up monster stats for the club beginning this fall.

15 15. Lewis Hamilton: $39 million

The 30-year old is a two-time Formula One World Champion who is racing royalty in that competition. Louis Hamilton has, in the past, been photographed ponied up alongside supermodels, and some in the racing industry have stated that they believe Hamilton could ultimately be one of the best in history. Former driver and current Sky Sports News analyst Nigel Mansell said the following about Hamilton in June 2015: “Everybody knows I am a Lewis fan and he is doing an outstanding job. Mercedes are the best of the best by far. With the backing of the Mercedes he can maybe go on to challenge Michael’s (Schumacher) record. There is a long, long way to go but it is possible because Mercedes will want to be the best of the best for a long time.”

14 14. Zlatan Ibrahimovic: $39.1 million

Even the most cynical of pro sports fan has to, at the very least, tip a cap to Zlatan Ibrahimovic and to those who have represented him over the years. Ibrahimovic has a long history of featuring for some of the biggest clubs in all of world football, and those teams have seemingly been happy to pay the front man impressive salaries to participate in competitions such as the Champions League. Rumors have been in the air for years that Ibrahimovic could choose to #DareToZlatan as a member of Major League Soccer. You can be sure that the eccentric Ibrahimovic would fetch a pretty penny from MLS to ensure his inclusion on next year's list.

13 13. Novak Djokovic: $48.2 million

It is, in ways, both good and bad to be the king of men's tennis. Novak Djokovic has emerged as the best in the business even though the 2015 French Open Final versus Stan Wawrinka did not go his way, and most will expect Djokovic to take care of business at Wimbledon during the summer months. The pressure that comes with being the best tennis player in the world can weigh on any athlete, one who is now more so chasing ghosts and his own legacy than he is merely attempting to win the biggest tournaments of every season. Djokovic will make a small fortune before he hangs his racket up for good. Where will we see him among other all-time greats when all is said and done?

12 12. Rory McIlroy: $48.3 million

There are similarities to be had when comparing the previously mentioned Novak Djokovic with Rory McIlroy. Both are wide perceived to be the next faces of their perspective sports, and both are seen as favorites whenever they enter a tournament. Those who hoped that McIlroy could evolve into the next Tiger Woods and serve as an injection of life into the game of golf would do well to remember that a Tiger Woods comes just once a generation at most. McIlroy can be a special player, yes, but labeling him as the next Tiger is downright unfair.

11 11. Ben Roethlisberger: $48.9 million

It was back in the fall of 2013 that whispers began circulating around NFL insiders that the Pittsburgh Steelers could consider unloading Ben Roethlisberger as part of a needed roster overhaul. The two-time Super Bowl champion then quieted all doubters with solid play over the subsequent dozen-and-a-half regular season games, so much so that the Steelers elected to instead do whatever possible to ensure that Big Ben remains with the club until he retires. What most expect will be Roethlisberger's final ever NFL player contract guarantees him $31 million, and that deal could be worth up to $87 million.

10 10. Kobe Bryant: $49.5 million

A facet of the sports world that is found in every league that guarantees amounts of money to athletes is that those in the twilight of their careers are going to be paid for past achievements. It is merely the lay of the land in the NBA, and thus Kobe Bryant checks in at tenth in the 2015 Forbes list. All indications are that Bryant, who already has a spot reserved for him in the Hall of Fame, will be but a shell of his former self if he is able to return to the court later on in 2015. Bryant is one of the best to ever play in the NBA, but his time as a top-tier athlete passed some time ago.

9 9. Tiger Woods: $50.6 million

A number of journalists and fellow golfers have, over the years, touched upon the competitive nature had by Tiger Woods. Woods has struggled mightily as of late, to the point that fans and golf journalists are believing that the all-time great may never again with a Major tournament. Woods will always be able to fall back on his millions – and millions and millions – of dollars that he has been paid throughout his career, but playing golf was never just about the money for Woods. His pursuit of immortality seems to have been abruptly halted.

8 8. Phil Mickelson: $50.8 million

No golfer, in this world of social media and of unprecedented televised sports coverage, has been a ratings draw quite like Tiger Woods. While Woods has had his detractors along with legions of fans during his career, Mickelson has been one of the more popular golfers of his generation. “Lefty,” as he has been affectionately called over the years, has found ways to revamp his game and remain competitive in top events up to this day, so much so that there are some who see Mickelson as a favorite to win the US Open this year. Make no mistake that people would tune in to see Phil get it done at TPC.

7 7. Kevin Durant: $54.1 million

As well off as Kevin Durant is heading into the summer of 2015, it is widely believed that his best financial payouts are to come once the NBA salary cap grows a couple of years down the road. Durant is going to have his choice of playing destinations in the future; Oklahoma City, the Los Angeles Lakers, the Washington Wizards or maybe even the New York Knicks just to name a few. Wherever he chooses to play out the bulk of his prime basketball days, Durant is only going to rise up such Forbes lists in the next several years.

6 6. LeBron James: $64.8 million

Remember what you just read about the future payouts Kevin Durant is going to see? The same goes for LeBron James and then some. James made an emotional return to the Cleveland Cavaliers in the summer of 2014, and he could, as of the posting of this piece, be on the verge of leading the Cavs to Cleveland's first pro sports championship in 51 years. The King of the NBA is not going anywhere anytime soon, but that does not necessarily mean that he will be giving the Cavs a hometown discount when 2016 rolls around. He and Cavs owner Dan Gilbert likely already have a deal set in place.

5 5. Roger Federer: $67 million

It has been an absolute joy to follow the career of Roger Federer since he first broke onto the tennis scene. One of the greatest players in the history of the sport will turn 34-years old in August 2015, and the tennis living legend has admitted that thoughts of retiring have made their way into his head as recently as this spring. Federer has proven that he still has enough in the tank to, at the very least, make significant runs in the top tournaments on the tennis calendar. Enjoy him while you can, because Federer's next run to a final of a Major may very well be his last.

4 4. Lionel Messi: $73.8 million

Is Lionel Messi realistically the best player in the world's most beloved game as of June 2015? Maybe not, but he can boast about being part of the Barcelona side that proved to be the kings of club world football for the 2014-15 European calendar. Messi, who will be 28-years old at the start of next season, likely has one more humongous contract in his future. Some have speculated that he will accept that from his current employers, while others have suggested that Messi could be lured to join up with a big-money side such a Manchester City if that team made the move worth his while.

3 3. Cristiano Ronaldo: $79.6 million

The best overall player on what is the wealthiest club on the planet is worth every cent that is spent on him, even if that club goes trophyless for a single campaign. Cristiano Ronaldo is more than just a footballing superstar who features for Real Madrid. Ronaldo has become a global brand similar to David Beckham in that his name is known throughout the world. Manchester United fans continue to cling to the hope that Ronaldo will make a return “home” to the Premier League outfit before he makes an expected move to Major League Soccer following the 2018 FIFA World Cup.

2 2. Manny Pacquiao: $160 million

On behalf of boxing fans and on behalf of individuals who forked over whatever amount of money necessary to watch the biggest letdown in boxing history: Cheers to you, Manny Pacquiao. Cheers for attempting to take it to defensive boxer Floyd Mayweather while at the same time allegedly doing so while nursing a bum shoulder, an injury that you conveniently said nothing about in the weeks and days leading up to what had been advertised to be the “Fight of the Century.” Pacquiao and Mayweather both made their money off of that fight, and it was the fans who, as happens far too often in sports, were left wanting more.

1 1. Floyd Mayweather: $300 million

He is not known as “Money Mayweather” just because it is his gimmick. Mayweather has made a living off of marketing and competing in pay-per-view events, and that was the case earlier in 2015 when he participated in a fight that left the majority of fans feeling cheated out of their cash. The truth of the matter is that nobody can realistically blame Mayweather for what occurred on that fateful night. Mayweather is a defensive fighter more interested in winning than in entertaining audiences, and thus everybody should have known what they were going to get when the head of the “Money Team” faced Manny Pacquiao.