Ultimate Fighting Championship and Pancrase Mezger began his
mixed martial arts career in the
Ultimate Fighting Championship at
UFC 4 in an alternate match against Jason Fairn. Before the fight, Mezger had asked Fairn to make a 'gentlemen's agreement' not to pull hair due to the fact both men had long hair. Mezger won the bout by TKO after landing a multitude of strikes from
full mount. Mezger next fought at
UFC 5 in an alternate match against John Dowdy, defeating him by
TKO in little over two minutes by mounted strikes. Mezger began to train with
Ken Shamrock and became a member of Ken's submission fighting team, the
Lion's Den, and joined the
Pancrase organization in Japan. In his second match at the Pancrase 1995 Anniversary Show, Mezger faced Pancrase co-founder and Shamrock's trainer
Masakatsu Funaki. The American fighter performed well, scoring high kicks and forcing Funaki to pull
guard and work from the bottom, but he was eventually caught in a leglock exchange from his own trip and submitted with an
Achilles lock. In December 1995, Mezger was involved in a controversial match against the other Pancrase co-founder, lauded wrestler
Minoru Suzuki. Mezger controlled the match, but he landed an accidental kick to the groin at 7:15 in the first round and was disqualified by the referee. His corner protested and defended the accidental nature of the strike, but the result was not changed. Guy's personal record shows it as a no contest. Nonetheless, Mezger accumulated a Pancrase 16–7–2 record and become the 7th ever
King of Pancrase world champion with a win over
Masakatsu Funaki. Mezger would not return to the
UFC until
UFC 13 where he competed in the Lightweight Tournament (200 lbs & under). In his first bout, Mezger fought top ranked judo fighter,
Christophe Leininger. Leininger was able to score a takedown and gain mount at one point, but he was otherwise soundly beaten as Mezger battled his way to a decision victory. Mezger broke his hand during this fight but continued in the tournament. The championship round Mezger faced future
UFC Light Heavyweight Champion Tito Ortiz. Ortiz was able to counter Mezger's takedown attempt and landed several knees to Mezger's head. To some it appeared that Mezger had tapped, but referee John McCarthy ruled Mezger was blocking the knees and his hand went down as Ortiz shifted his weight. The bout was then stopped to check Mezger's cut. The announcers, as well as Ortiz, thought that the bout was over, but the fight was instead restarted on the feet. Ortiz shot in for a takedown, but Mezger secured a
guillotine choke, forcing Ortiz to submit. With this win, Mezger became the
UFC 13 lightweight tournament champion. 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.
PRIDE Fighting championships The former
UFC champion made his Pride FC debut in 1999 at
Pride 6 against the popular
Akira Shoji. The two fighters passed most of the first round in the clinch, where Mezger landed strikes and tried unsuccessfully to take down Shoji. At the second, Akira scored a takedown and performed
ground and pound, which Mezger retaliated by controlling the striking again when they returned to their feet; however, the Japanese took Mezger's back on the ground towards the end of the round and scored punches while Guy attempted to escape. At the third and final round, the two traded strikes again and Shoji repeated his back siege before the fight ended. The judges decreed a split decision and it was given to Shoji. Pride officials then signed Mezger to fight
Kazushi Sakuraba, who at the time was considered to be one of the best
pound for pound fighters in the world. The fight took place at the
Pride Grand Prix 2000 Opening Round. Mezger took the fight on two weeks notice and had a broken foot going into the fight. The contract that Mezger signed stipulated that the fight would be one 15-minute round with no overtime, in contrast to the other fights which were to have an extra round in the case of a draw. The fight mostly consisted of Mezger controlling the fight by stopping Sakuraba's takedown attempts while landing strikes from the outside. The round ended and Mezger expected the fight to go to the judges, but Pride officials wanted the fight to go to overtime. This resulted in one of the largest and most publicized controversies in MMA history. According to Mezger, Pride did not like the outcome of the fight and changed the agreement/contract on the spot in order to give Sakuraba another chance to win the fight. An argument ensued and Mezger was ordered out of the ring and back to the locker room by his corner man,
Ken Shamrock, who was livid at the decision to extend the fight because of Mezger's foot injury and the fact that he took the fight on short notice. Later that night, the president of Pride FC made a public apology to Mezger at the Tokyo Dome for the miscommunication. Mezger added, "Royce's father came up to me after my fight and said, "You got screwed. You won that fight." Here's Helio Gracie walking up to me and telling me I got ripped off." Mezger next competed against
Masaaki Satake, winning the fight by unanimous decision. Mezger made his return to the ring at
Pride 10 - Return of the Warriors, facing Brazilian superstar and future middleweight kingpin
Wanderlei Silva. Mezger gained the upper hand early, cutting Silva with several crisp combinations and outpointing Silva on the feet. However, he was ultimately knocked out at the 3:45 mark. Shortly before the knockout, Silva was catching the worse end of the punching exchanges and proceeded to throw an intentional, illegal headbutt to Mezger that eventually led to landing the knockout combination. Many people felt as though this was a cheap shot that affected the end result. Some people, including
Kazushi Sakuraba, felt the bout should have been changed to a
no contest. Mezger talked about his feelings on the matter in an interview: "I am not going to cry foul, it is the fight game and things like that happen, get used to it. It is no win situation when it comes to answering that question, if I said it did (affect the result) then I would be making excuses. I would just like a rematch." In December 2001, Mezger was proposed the idea of fighting at Inoki Bom-Ba-Ye while wearing
Tiger Mask's attire and mask, but he didn't accept. Thus, Mezger returned to competition at
Pride 22 after a year long lay-off, easily winning a decision over Norihisa Yamamoto. Mezger then battled
Antônio Rogério Nogueira at
Pride 24. Mezger had several good striking exchanges and showcased his submission and takedown defense, but again lost the fight by a controversial split decision. == Retirement ==