Despite the defeat, Bustamante had done enough to move down to the middleweight division and challenge Menne for the 185-pound title, which he did in definitive fashion via second-round TKO at UFC 35. He would follow that performance with a successful title defense four months later at UFC 37, where he submitted Matt Lindland via guillotine choke in the third round.
In that fight, Bustamante tied Lindland up in a tight armbar, and Lindland appeared to tap in the first round. In a bizarre sequence of events, Lindland disputed and said he never tapped, and referee John McCarthy allowed the fight to continue. It took another round of work, and Bustamante admitted to fighting angrily in the second round, but eventually, his jiu jitsu prowess produced the justice he deserved.
Bustamante would vacate the title afterward, opting to compete in Japan under the PRIDE banner, where he would continue his career until 2007, fighting the likes of Dan Henderson and Quinton “Rampage” Jackson. In 2005, Bustamante reached PRIDE’s Welterweight Grand Prix Final, ultimately falling to Henderson via a razor-close split decision.