FRANKFURT, Germany (AP) — Wladimir Klitschko has invoked a contract clause calling for a rematch with Tyson Fury in an attempt to regain the heavyweight title he lost to the British fighter.

Fury took away Klitschko's four titles in a stunning unanimous decision in Duesseldorf on Saturday night, ending the Ukrainian's 9 ½-year reign as champion.

"It's fantastic news, we are ecstatic," said Peter Fury, the uncle and trainer of the new champion.

Fury is obliged contractually to accept a rematch, he said. Peter Fury suggested holding the new fight in England, possibly at Wembley Stadium.

Fury took Klitschko's WBA, IBF, and WBO heavyweight belts, as well as the minor IBO title. Klitschko had been unbeaten since April 2004.

"I was really frustrated directly after the fight but after some short nights I now know that I want to show that I am much better than my performance on Saturday," Klitschko said in announcing plans for the rematch.

"I couldn't show my full potential at any time. This is what I want to change in the rematch — and I will. Failure is not an option."

Klitschko's management team says it will get in touch with Fury's promoter to set the venue and date for the rematch.

"There will be a huge worldwide interest in this fight which already can be billed as the fight of the year 2016," said Klitschko's manager Bernd Boente.

Klitschko turns 40 in March. Fury is 27 and 2.09 meters (6-foot-9) tall.

Klitschko, who is 1.98-meters (6-foot-6), was in the unusual position of facing someone taller. Fury, who weighed in at 112 kilograms (247 pounds) also had half-kilo (1.1 pound) weight advantage for the fight.

The Ukrainian dropped to 64-4, with 53 KOs, while Fury improved to 25-0, with 18 KOs.