When you book a fight, you ultimately have two options on how to approach your opponent. You can go train, do your thing, be respectful, shake hands, and fight. When the fight is over, you can go get a drink or simply hug and walk away. This approach will let your skills do your talking for you, and will avoid any kind of unpleasant situation. However, it may negatively impact the popularity of your fight. Alternatively, you can insult your opponent in every way imaginable, fight out of emotion, and create yourself a new enemy.

For some fighters, this second option seems a lot more attractive. Many who choose this approach do so in order to sell their fight. After all, more buys equals to a bigger payday. Others do it to create a name for themselves in order to become famous or feared in the MMA community.

However, not all fighters create scenes and trash talk in order to generate sales: some do it because they genuinely hate each other. These hateful feelings are created in a variety of ways: feuds between training camps, personal insults or, most commonly, coaching on The Ultimate Fighter. For these fighters, the payday and the fame no longer matter: they want to fight each other out of hate, and the trash-talk naturally follows. No matter how these rivalries got started, these athletes hated each other before they fought, and still have each other years after their bout. Here are the top 15 MMA fighters who hate each other:

15 15. Matt Hughes and Matt Serra

After Serra defeated Georges St-Pierre, he almost instantly started calling out Hughes. However he did so in the least respectful way possible, calling him a "d*ck of a person" and saying he has absolutely no respect for him. Matt Hughes gave into the trash talk, and started saying that he wants to slap Serra in the face to shut him up. This feud led to a great fight, but the two Matts still are not very good friends.

14 14. Jon Jones and Rashad Evans

When Jones first started out in MMA, he was mentored by Rashad Evans. The two guys were teammates and friends, until one day Jones announced that he would have no problem fighting Rashad Evans. Since their team had a rule of not fighting each other, Evans saw Jones as a traitor, and hated him from that moment on. A lot of emotion was brought into the octagon when the two men finally fought, but Jones went home with a dominant decision victory.

13 13. Kazushi Sakuraba and the Gracie family

For a long time after UFC 1, the Gracies seemed unbeatable due to a new style of fighting that has been introduced to North America and the rest of the world. However, one man beat almost all the members of this legendary Jiu-Jitsu family, a man nicknamed "The Gracie Hunter." When he fought a Gracie, the Jiu-Jitsu fighters were respectful, but always fought with a desire for vengeance and with a particular hatred towards the Japanese wrestler.

12 12. Ronda Rousey and Bethe Correia

When it was announced that this bout is to take place in Brazil, Correia took the fight a little too personally, thinking that Rousey wanted to invade her country and her people. This led to an onslaught of insults coming from the challenger, saying that Ronda could never take one of her punches and is in for a rude awakening. Pretty ironic, when we look at the outcome of the fight. Still, after the fight, Correia promised to work her way back to the top and get another shot at Rousey in 2016: we'll just wait and see if that ever happens.

11 11. Wanderlei Silva and Chael Sonnen

It was a sad day when Silva ran away (literally) from his random drug test ahead of his fight with Chael Sonnen, as that would have been a hell of a fight. These two spent a whole season of The Ultimate Fighter talking trash to each other, and even brawled on the set of the show. In fact, these two never had a proper stare-down without talking, screaming, or pushing. With Chael Sonnen currently making his transition to Metamoris, a submission grappling event, we can only hope that this fight will take place one day in a different organization.

10 10. Georges St-Pierre and B.J. Penn

GSP versus B.J. Penn was an awesome fight. While both MMA legends put on a spectacular performance, St-Pierre came out on top. This should have been the end of it, but it wasn't. After their bout, Penn proceeded to call St-Pierre a cheater and made several allegations that the former champion was using PEDs for a large part of his career. St-Pierre did not take kindly to these comments, and the two fighters have had a strained relationship ever since.

9 9. Daniel Cormier and Jon Jones

Before they fought, these two guys absolutely hated each other. They brawled in a crowded event, spoke death threats to each other, and trash-talked as much as possible. After their fight, these feelings did not go away. After being reinstated by the UFC, Jones immediately called out Cormier, saying that he would fight him in an unsanctioned fight at his gym to get the belt back, and Cormier accepted. Sounds like an innocent joke. But minutes after the "scheduled" fight, Jones took to social media with a phrase addressed to Cormier: "You on your way pu**y"?

8 8. Georges St-Pierre and Nick Diaz

St-Pierre has always been a humble and respectful champion, avoiding all unnecessary trash-talk and doing his talking inside the cage. However, Diaz somehow managed to bring out the "bad side" of GSP.  He even got the former champion to call him an "uneducated fool" and swear at him in French. After the fight, GSP tried to be humble by offering praise to Diaz, but Diaz kept talking trash. However, GSP did not engage in any talking after the fight, but still does not take kindly to Nick Diaz.

7 7. Ken Shamrock and Tito Ortiz

This feud started when Ortiz repeatedly insulted Shamrock's cornermen and flipped them off. At the time, Ortiz was a young and relatively unknown fighter, while Shamrock and his team were internationally famous. Therefore, Ortiz's remarks and insults angered Shamrock, who went absolutely crazy and was screaming and gesturing at Ortiz every time they saw each other. Ortiz won all three fights of the trilogy by TKO, but Shamrock still wants another chance to beat his long-time rival in Bellator.

6 6. Anderson Silva and Chael Sonnen

In this scenario, Anderson Silva is merely a puppet. The real hate lies between Chael Sonnen and every Brazilian fighter that has ever existed. Leading up to this fight, Sonnen talked trash about every aspect of Anderson Silva: his country, his wife and his fighting skills. Silva didn't retaliate at first (perhaps due to his very low level of English), but beat Sonnen twice after, solidifying his reign of the middleweight division. However, Sonnen still has bad things to say about Silva in recent interviews, even though Silva seems to have forgotten everything about these fights.

5 5. Frank Mir and Brock Lesnar

When we see Frank Mir in the octagon, we usually see a respectful and composed fighter with tons of sportsmanship, even a role-model perhaps. However, when talk comes of Brock Lesnar, that all changes almost instantly. Ever since Lesnar beat him in 2009, Mir has been campaigning for a third fight, stating that he absolutely hates the former champion. Mir even went as far as saying that he wants Lesnar to be the first man to die inside the octagon.

4 4. Rampage Jackson and Rashad Evans

When your teammate loses a fight, what do you do? Do you point out his mistakes, do you console him? According to Rampage Jackson, you break down doors and walls. On the set of The Ultimate Fighter, Jackson and Evans had a furious competition but eventually Evans' team absolutely dominated. Yet, Jackson had his mind set on revenge, as he was scheduled to fight the former champion later that yet. Rampage lost that fight, but never really lost his hateful feelings towards Rashad Evans.

3 3. Ronda Rousey and Miesha Tate

Here is another crazy rivalry that reached its peak levels on The Ultimate Fighter. During their time coaching on the show, Rousey and Tate kept talking trash to each other back and forth, hyping up the rematch between the two fighters. When they finally fought and Ronda finished take with an arm bar, Miesha tried to remain humble and shake Ronda's hand, a gesture to which the champion simply walked away. If these two can't become friends after such a fight, I guess it's simply not meant to be.

2 2. Chuck Liddell and Tito Ortiz

Yeah, ANOTHER rivalry sparked by The Ultimate Fighter. This show can really help fighters respect each other or can turn them against each other rather quickly. Leading up to the show, Liddell had already knocked out Ortiz twice before, and was scheduled for a third fight against his rival. However, this did not make Ortiz respect Liddell one bit. The two legends engaged in a fierce competition during the show, but Ortiz had to pull out of the fight due to a neck injury. When Liddell found out about this, he went absolutely crazy, and started to hate Ortiz even more.

1 1. Jose Aldo and Conor McGregor

If you say that I'm just hyping up UFC 194 by ranking these guys at #1 well...you just might be right. Nevertheless, this fight can't come soon enough. For several months now these two top level fighters have been talking trash to each other and, when Aldo injured his rib ahead of their originally scheduled fight, the trash talk grew even louder. While McGreg0r keeps claiming that Also won't show up for their scheduled bout in December, Aldo is keeping calm and training as much as he can in anticipation of this fight. However, even the champion can't seem to stay away from some trash talk, saying that "I'm going to kill this mother****** and cut his head off."