Mantaur wrestled his first two matches in the World Wrestling Federation (WWF) as Bruiser Mastino, defeating Nikolai Volkoff on August 25 and 26, 1994, at house shows. A few months later on the January 7, 1995 episode of Superstars of Wrestling (taped on December 10, 1994), Mastino debuted as Mantaur, defeating Walter Slow. The Mantaur character was that of a Minotaur who charged, trampled and mooed at opponents. Soon after debuting, he acquired Jim Cornette as his manager.
Mantaur then began a small winning streak, defeating a series of jobbers. He came close to beating then-Intercontinental Champion Razor Ramon, but lost the match by disqualification due to interference by Jeff Jarrett, who was involved in a feud with Ramon at that time. Mantaur made his first and only pay-per-view appearance at the 1995 Royal Rumble, where he competed in the Royal Rumble match and lasted nine minutes before being eliminated by Lex Luger.
Mantaur was defeated by WWF World Champion Bret "The Hitman" Hart during a taping of Wrestling Challenge in Moline, Illinois on April 26, 1995.
Mantaur entered the 1995 King of the Ring tournament, but was pinned by Bob "Spark Plug" Holly in a qualifying match. In his final televised WWF match, he lost to Bam Bam Bigelow as part of a push to enhance the popularity of Bigelow as a babyface. Mantaur made his last WWF appearance as a lumberjack in a lumberjack match between Sycho Sid and Diesel at In Your House 2.
After leaving the WWF, Mantaur returned to his Bruiser Mastino ring name and joined Extreme Championship Wrestling. He debuted there on December 1, 1995, with a victory over The Dark Ninja. Eight days later, he lost to Hack Meyers at December to Dismember. A few weeks after that, he lost to 911. At Holiday Hell, Mastino defeated El Puerto Ricano in his final match for the promotion, in which he was jeered with "Mantaur" chants from the always-vocal ECW audience.
In April 1996, he returned to the WWF playing the role of Goldust's unnamed bodyguard. He appeared with Goldust at In Your House 7 in his corner for his match against the Ultimate Warrior. After Goldust lost, the bodyguard attacked Warrior but was overpowered and body slammed.
He returned to the WWF in June 1997 with the Truth Commission, under the ring name Tank. He wrestled on two Shotgun Saturday Night episodes until his release later that summer.
He wrestled one dark match for World Championship Wrestling's Monday Nitro, defeating Damián on September 22, 1997, in his only appearance for the company.
Mantaur passed away on July 11, 2023.