21 of the biggest rivalries in MMA history [UPDATED]

UFC 229: Khabib v McGregor Press Conference
UFC 229: Khabib v McGregor Press Conference / Steven Ryan/GettyImages
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Brock Lesnar and Frank Mir

Sometimes big rivalries stem from big personalities, at least that is the case for our next rivals. Brock Lesnar is one of the biggest men to step foot in the Octagon when he came over from the WWE he had all eyes on him right away. A former champion in the WWE, Lesnar had a strong fan following and had a lot to prove now that he was making the transition over to mixed martial arts. He was set to make his UFC debut at UFC 81 in Feb. 208. His opponent was none other than Frank Mir.

Mir at the time was a longtime vet of the UFC light heavyweight division and a former champion. Mir had his UFC title taken away after he suffered a motorcycle accident. Mir was working his way back up to a title shot when he was faced with Lesnar. At the time Lesnar had to wear a size 4X glove, the biggest by any fight in UFC history. That fact didn’t help him much as Mir was able to submit Lesnar in the first round of the fight. After the loss, Lesnar went on to win the title after he defeated Randy Couture at UFC 91. In the meantime, Mir won the interim title and immediately called out Lesnar. The two were set to meet again at UFC 100. This time it was Lesnar who won, by second-round TKO.

Mir finished up his time in the UFC and moved on to Bellator. Lesnar has had some trouble with drug testing and has since moved back to the WWE. The two never had the chance to fight again, but the rivalry continues. Mir spoke about a possible third fight between the two on his podcast Phone Booth Fighting, suggesting that it is not too late for them to mix it up a third time, but that's highly unlikely.