Tony Ferguson may now be the interim UFC lightweight champion. But, the knockout of Ferguson's career took place some time ago. Most impressively, Ferguson got the knockout from his back. Back in 2011, "El Cucuy" competed on The Ultimate Fighter: Team Lesnar vs. Team dos Santos. Ferguson would go on to win the reality show with a knockout finish over Ramsey Nijem in the season's finals. However, it was Ferguson's knockout finish over TUF competitor Justin Edwards that has snared the attention of many fight fans. Ferguson found himself on his back during the fight, with Edwards trying hard to get in a dominant position for some ground and pound over his opponent. However, Edwards then stood up and began leaning over Ferguson. "El Cucuy" retaliated with a fight ending up kick that knocked Edwards out cold. Check out the stunning knockout finish in the video above. For more MMA news click here.