Brock Lesnar quickly proved that he wasn’t just a pro wrestling star looking for some camera time in the UFC. Just three fights into his MMA career, Lesnar (5-3-1 MMA, 4-3-1 UFC) challenged heavyweight champion Randy Couture at UFC 91 in 2008 and confounded the doubters by finishing the legend to win the UFC heavyweight title. The two started out by exchanging positions in the clinch, with Lesnar eventually dragging the fight to the mat multiple times.