Last month Nationals’ fielder Bryce Harper waltzed into spring training in Florida and told Washington sports reporters what they've been dying to hear for nearly a quarter-century: “I’m gonna bring a title back to D.C.” Say what? He’s already asking “Where’s my ring?” and is chomping at the bit to “hoist that trophy over the monuments.” But sports journalists from both D.C. and abroad know best to believe it when they see it. The Washington Redskins haven’t had a Super Bowl sniff since their 1991 victory. The Washington Capitals came close to a Stanley Cup in 1998 but were swept in the final, and havem't come close since. And well, we’ll just leave the Wizards out of the conversation for now. (We’re just talking about the big-four leagues here, D.C. United fans. Calm down. We all saw your 2004 MLS Cup win.)

Harper is certainly not the only Nostradamus-wannabe throughout sports history. What really matters, though, is whether the predictor can back up his words. Any loud mouth can guarantee a victory, but whether he comes through at game time is another story. Not all players, unfortunately, can pull off a Babe Ruth and (allegedly) call a World Series home run shot. But one thing's for sure: players since the Great Bambino’s time are not short on swagger.

Sometimes shooting off the lip pays off—a Bill Parcels Super Bowl pep talk—and sometimes it doesn't—anytime Sean Avery opens his trap. But in order to excel at the highest level of sports, you need confidence and that competitive edge. And while having players on the team that lead by example is one thing, clubs also need that guy who will stand up in the locker room (or in front of the media) and say what needs to be said. For better or worse, here are the top 10 most memorable predictions in sports history.

10 10. Dan Gilbert’s Personal Guarantee to Cavs Fans

In a move that he’s since admitted he regrets, Cleveland Cavaliers owner Dan Gilbert addressed fans in an open letter following Lebron James's 2010 departure to Miami, personally guaranteeing an NBA championship “BEFORE THE SELF-TITLED FORMER 'KING' WINS ONE.” Yes, he used all-caps. “You can take it to the bank,” he wrote. Miami would win back-to-back championships with Lebron, while Cleveland failed to make the playoffs in all four years sans Lebron. And the Cavs have since welcomed their king back with somewhat-open arms. “Looking back now, that probably was not the most brilliant thing I've ever done in my life.” At least you’re honest, Dan. You probably should have slept on that letter.

9 9. Hasselbeck Wants the Ball and He’s Going to Score

This one was relived endlessly by the media following Seattle’s Super Bowl goal line choke, but a classic prediction-gone-wrong cannot be missed. It was a game that seemed meant to be for the Seahawks, who squeaked into the postseason with an NFC wild card spot against Green Bay. A late 4th quarter touchdown for Seattle would force overtime, and following the coin toss which the Seahawks won, quarterback Matt Hasselbeck stated, “We want the ball and we’re going to score!” The referee’s mic caught it all, and so did everyone watching at home. They also watched Packers’ cornerback Al Harris intercept the ball and run it back 52 yards for the win. In fairness to Hasselbeck, his play did lead to a score, so he was half right.

8 8. Charles Barkley: “God Wants Us to Win”

In a post-game interview following Game 5 of the 1993 finals versus Chicago, Charles Barkely, then with the Suns, claimed to have spoken with the Lord himself, who apparently was a Phoenix fan. But when you’re a league MVP you get to make bold statements, right? Unfortunately for Barkely (and God apparently), the Bulls won in Game 6, capping the championship three-peat. Michael Jordan, on the other hand, fared much better with his playoff guarantees. Going into Game 7 of the 1998 Eastern Conference finals against Indiana, Jordan declared, "We will win Game 7." And so they did, going on win yet another back-to-back-to-back championship, in Jordan’s last playoff appears with the Bulls.

7 7. Zambrano Promises to End the Curse

Chicago Cubs pitcher Carlos Zambrano entered the 2007 season on a high: most NL league wins, fifth in Cy Young voting, and a trip to the All-Star Game. The Cubbies, unfortunately, finished dead-last. But that didn't stop Zambrano from promising Cubs fans their first World Series in a century. “I guarantee that. I have faith in that.” It was clear that he regretted the comment, though, he amended his guarantee to "I’m almost sure. I promise I will do the best I can.” That’s a bit more realistic, Carlos. It was a valiant effort, finishing the regular season atop the NL Central, but the Cubs would fall in the division series to Arizona. You wonder if the Chicago fans believed a word of it.

6 6. Colin Kaepernick Predicts Stardom with 49ers

How’s this for a crazy prediction? As a fourth-grader, Colin Kaepernick peeked into the future and saw himself suiting up in the scarlet and gold. “I hope I go to a good college in football then go to the pros and play on the Niners or the Packers,” Kaepernick writes in a letter, “even if they aren't good in seven years.” What a good future teammate. He also predicted his height as an adult—6-foot-4—although his target weight of 190 pounds would prove about 40 pounds shy. Maybe after Kaepernick's career is over, he can find a second career as a psychic.

5 5. Atlanta Hawks’ Big Playoff Gamble

This is one sports guarantee that was literally a gamble. Hoping to turn things around in 2002, Hawks head coach Lon Kruger attempted to set the bar high with a ballsy declaration: Atlanta will qualify for the playoffs and season ticket holders will be given free Game 1 tickets. Failing that, ticket holders would be given a $125 refund. Well, failed they did. Atlanta finished 11th in the conference and Kruger was fired before the half-way point of the season. With an obligation to around 4,000 season ticket holders, the Hawks shelled out about $500,000. At least Kruger taught us a great way to get yourself fired is wasting your boss's money.

What was dumber? That, or Jackie Moon promising free corn dogs to Flint Tropics fans?

4 4. Rex Ryan: “We’re going to win the Super Bowl”

You can always count on Rex Ryan for a quality failed prediction. His best, though, has to be his 2011 Super Bowl guarantee. After making the same prediction for the previous two years, and hoping to improve on a 11-5 record, this one seemed to be the best bet. But like the years prior, it was not to be. In fact, the Jets finished the season 8-8 and didn't make the postseason. The fallout from the guarantee would burble into the offseason, when LaDainian Tomlinson said Ryan's statements put too much pressure on the team. Rex Ryan, agreeing to “tone down” the commentary, would later come to regret the guarantee: “Guaranteeing that Super Bowl is always going to haunt me.” Will we ever hear him utter these words in Buffalo?

3 3. Muhammad Ali Predicts the Round he Knocks ‘em Down

You can’t make a list of memorable sports predictions without including the undisputed champion of pre-fight banter. Making his poetic predictions a thing of art, Ali routinely guessed the round he’d knock out his opponents before most bouts. “Not only do I knock them out, I pick the round,” the Louisville Lip quipped. His predictions were correct in fights against Archie Moore and Henry Cooper, but it was a rematch versus Sonny Liston, when Ali guaranteed a first-round KO, that takes the cake.

2 2. Joe Namath’s Guarantee for the Ages

"We're gonna win the game. I guarantee it.” Those eight words would unite a team ahead of one of the biggest upsets in Super Bowl history. Going into the 1969 championship game against the powerhouse Baltimore Colts—13-1 in the regular season and advancing to the Super Bowl with a 34-0 rout against Cleveland—the Jets had their work cut out for them. But the famous prediction nearly didn't happen, and only came up when a loud mouth Colts fan heckled Namath three days before the game. The Jets went on to win 16-7. 

1 1. Mark Messier: “We’ll Win Tonight”

It’s one thing for a nobody on the team to make a guarantee, but it takes some guts for Mark Messier—captain of the 1994 New York Rangers—to promise a Game 6 victory against New Jersey to stave off elimination. It’s not like he merely whispered it to a teammate either, as the declaration was plastered on the cover of the New York Post. But what makes the guarantee most epic and what gives it the top spot was Messier’s performance to back up his words. Not only did the Rangers win 4-2, but Messier’s hat trick lead the way. New York would go on to win the series, then beat Vancouver in the finals for their first Stanley Cup since 1940.