In 1991, he joined the World Wrestling Federation (WWF) as The Viking. He soon became The Berzerker (managed by Mr. Fuji) and feuded with Davey Boy Smith and Jimmy Snuka. His preferred method of winning matches was by throwing his opponents over the top rope for a countout, all the while holding his wrist, licking his hand, shouting "Huss! Huss!", and falling flat on his back. He wrestled as part of a 4-man team in an elimination match at the 1991 Survivor Series pay-per-view event. He was the last man eliminated for his team. He then feuded with The Undertaker, at one point attempting to stab him with his sword. In July 1992, he won a 40-man Battle Royal on WWF Prime Time Wrestling, and challenged Bret Hart for the WWF Championship that November. He left the WWF the following year.