Abbott started his career in mixed martial arts when he applied to the
UFC for its event
UFC 6 in
Casper, Wyoming. He was introduced to the UFC management by his future manager Dave Thomas, who credited him as a veteran street fighter who lifted 600lbs in
bench press and had knocked out four men in his last brawl. Upon this description, the management compared him to the character "Tank Murdock" from the 1978
Clint Eastwood movie
Every Which Way But Loose, which encouraged them to give David the nickname of "Tank Abbott" and bill him as a "pit fighter" with over 200 street fights. According to Abbott, this wasn't the first time he applied to the UFC. Inspired by
Kimo Leopoldo's participation in
UFC 3, he had tried to enter the promotion as soon as September 1994, but the UFC management only allowed him to fight from
UFC 6 onwards, after
Royce Gracie had ceased fighting in UFC.
Art Davie would later confirm the
Gracie family used its input in the management to limit fighters with
amateur wrestling backgrounds, like Abbott himself, from entering the first events.
Ultimate Fighting Championship (1995–1998) Abbott made his debut at UFC 6 in July 1995 as scheduled. He actively cultivated the tough character he had been given, firstly by giving a rude interview in which he derided
martial arts and then by knocking out the Hawaiian
Kapu Kuialua fighter John Matua, who weighed 400 lb, in the first 18 seconds of his opening fight. Abbott further solidified his reputation by mocking Matua's convulsions after the KO while the ring doctors rushed the cage. Abbott advanced to the next round and was pitted against a similarly heavier adversary,
Paul Varelans. After returning to the cage in midst of strong cheers, Abbott knocked out Varelans by
ground and pound and
knee strikes, all while mockingly smiling at his opponent laying beneath him. At the finals of the tournament, Abbott faced the Russian
Oleg Taktarov in a fight that the announcers touted as a "skill vs. power" bout. Just as described, the match saw Abbott blocking Taktarov's artful grappling attempts and damaging him in turn with hard punches and
uppercuts. With both men becoming increasingly tired due to their previous fights and the high altitude of the location, the action moved to Taktarov's
guard, where Abbott avoided multiple submission attempts and punished him further. The fight was restarted standing, which would give Abbott the advantage, but by this point he was exhausted enough for a slightly better conditioned Taktarov to pull him down and lock a
rear naked choke, thus winning the fight at the 17 minutes mark. Both men collapsed in exhaustion after the fight, and Taktarov had to be carried out of the cage. Abbott's next UFC appearance would be in September 1996, at
UFC 11. Accompanied by a young
Tito Ortiz and dragging a knee injury without adequate surgery, According to Abbott, Ferrozzo had to go to the hospital after the match, while he did not. Abbott claimed he made a mistake by letting Frye get his hooks in, as he would have been planning to use them to snap his ankles. Ultimate Ultimate 1996 was the last UFC tournament in which Abbott partook, as around the same time the UFC began switching away from the tournament format. Abbott's fortunes declined with the arrival of better trained
mixed martial artists, who posed a much bigger challenge than the previously inconsistent opponents from the earlier UFC events. In October 1997, Abbott was contacted to fight in the Japanese
Pride 1 event against
Kimo Leopoldo, but he was unable to do so, having to be replaced by
Dan Severn. Ironically, shortly after Abbott replaced Severn himself with four days notice in a title match for the
UFC Heavyweight Championship against
Maurice Smith at
UFC 15, a circumstance he described as "literally falling off the barstool into the octagon." Trying hard to press the action, Tank shockingly dropped the kickboxing champion with an early shot, but Smith controlled him through his defensive guard and a
Kimura attempt. The action was restarted standing, but by this point Abbott was exhausted and offered little resistance to Smith's
low kicks, prompting the referee to stop the match. Abbott bounced back from his losses with his performance at the first UFC show on Japanese soil,
UFC Japan, where he was pitted against
shoot-style wrestler
Yoji Anjo. The American dominated the match with takedowns and right hands, avoiding submission attempts with short bursts of ground and pound every time they hit the mat, which eventually gained him the unanimous decision win. The event featured a tournament format, but Abbott forfeited due to a broken hand acquired while punching Anjo. Back in the United States, at
UFC 17, he followed with an impressive victory over renowned
luta livre fighter Hugo Duarte, who was famous for his
vale tudo fights against
Rickson Gracie. Duarte had previously criticized Tank and his fighting skills, and he came close to proving himself right by almost locking a rear naked choke and an
armbar in the first few seconds. However, Abbott blocked them successfully and captured Duarte's back, landing heavy punches from there, completely knocking the Brazilian out. At the same event, Tank was suspended by UFC for verbally fighting with
Allan Goes, which according to Abbott happened because he had cheered for the opponent of Goes's teammate
Wallid Ismail at
UFC 12. Abbott praised Rizzo after the match, although he claimed to believe the cage canvas had been greased to hinder the footing of wrestlers like him. His next fight would be against fellow UFC veteran,
Kimo Leopoldo at
UFC 43. Abbott was taken down seconds into the fight, and was submitted via
arm-triangle choke. Abbott then faced
Wesley "Cabbage" Correira at
UFC 45. After a back-and-forth brawl, Abbott lost the fight via TKO after the ringside doctor determined he was unable to continue after suffering a cut over his right eye. Abbott and his corner got into a minor brawl with Correira's team after being angered by Correira's taunting when being declared the winner. Abbott was released from the UFC afterwards. Abbott later had a rematch with Correira, at Rumble on the Rock 7. Abbott secured his first victory since his return, knocking Correira out with a hard right hand in the first round, becoming the first person to knock Correira out. Abbott's next fight was on August 28, 2005, against highly decorated
judoka
Hidehiko Yoshida at
Pride Final Conflict 2005. Abbott lost via single wing choke submission in the first round. Abbott's next fight was against
Paul Buentello, headlining
Strikeforce: Tank vs. Buentello on October 7, 2006. Abbott lost via knockout 43 seconds into the fight. Abbott then fought
Gary Turner at the main event of
Cage Rage 21 on April 21, 2007. Abbott lost via TKO after a barrage of punches from Turner early in the first round. Abbott's last high-profile fight was against
Kimbo Slice in the main event of
EliteXC: Street Certified. Abbott was knocked down early, but the fight was restarted after Kimbo landed shots to the back of Abbott's head. Abbott would lose the bout via knockout seconds later. His next fight was against former
PRIDE veteran Mike Bourke on February 13, 2009, at the
Selland Arena in
Fresno, California, as part of the Valentine's Eve Massacre Event. Abbott knocked out Bourke with a punch that inadvertently landed to the back of Bourke's head, securing a victory for the first time in nearly four years. In 2011 Abbott participated in an unsanctioned "backyard brawl" against
Scott Ferrozzo, whom he previously fought at
UFC 11. Abbott knocked down Ferrozzo early with a punch, before taking his back and holding dominant position for over 15 minutes, occasionally landing punches. He was declared the winner via unanimous decision. Bouncing back with a win following his loss to Slice, At
King of the Cage: Fighting Legends, on April 13, 2013, Abbott fought for the Superfight Championship. He was defeated by longtime veteran Ruben "Warpath" Villareal by way of a 2nd-round TKO. Abbott was expected to face fellow MMA veteran
Dan Severn for the upstart UR Fight promotion on March 20, 2016. The contest was cancelled the day prior to the event as Abbott could not pass the required medical tests per the Arizona Fight Commission. ==Professional wrestling career==