Mezger then forfeited his King of Pancrase title to fight in the UFC again. Mezger's final bout in the UFC was a rematch with Tito Ortiz at UFC 19: Young Guns. Mezger was sick before the fight but fought anyway, a decision that he regretted after the fight. This resulted in Ortiz handling Mezger and won the bout at the 9:55 mark by referee stoppage. The stoppage was somewhat controversial because both Mezger and his cornerman Ken Shamrock felt that Ortiz's strikes were not doing enough damage to warrant a stoppage. Ortiz then donned a shirt that was insulting to Mezger which provoked an immediate reaction from Ken Shamrock, Mezger's trainer. Mezger would occasionally seek a rematch with Ortiz over the next few years. In 2004 he was finally granted a chance to face Tito Ortiz at UFC 50. Unfortunately, the week of the fight, Mezger was taken to the hospital due to stroke like symptoms, and was taken off the fight card.