7#7 Frank Mir vs. Brock Lesnar
Mir and Lesnar have an even record against each other, with each fighter holding one victory against the other. Brock Lesnar was already famous thanks to his stint in the WWE and for being a ridiculously imposing figure in general.
Lesnar was booked to face Frank Mir in his UFC debut at UFC 81 in 2008, which is a tall order for someone’s 2nd MMA fight ever - even if your name is Brock Lesnar. Perhaps unsurprisingly, Mir used his superior jiujitsu to submit Lesnar in the 1st round with a knee bar. Lesnar won his next fight against Heath Herring, and was then booked for a title fight against heavyweight champion Randy Couture.
Lesnar became the UFC heavyweight champion, stopping Couture in the 2nd round via strikes. He was subsequently injured and had to take time off, during which Frank Mir became the interim UFC heavyweight champion. At UFC 100 in July 2009, their rivalry came to a head during their title unification match. Mir resented the fact that Lesnar was quickly pushed up the ladder by the company brass, publicly stating that he wanted Lesnar to be the first death in the octagon. Their actual fight was a more one-sided affair, with Lesnar dominating Mir and becoming the undisputed UFC heavyweight champion. The bad blood helped sales though - UFC 100 is by far the company’s best-selling PPV ever.