Sources: Tyson Fury, Oleksandr Usyk sign on for winter showdown

Tyson Fury and Oleksandr Usyk have signed contracts for an undisputed heavyweight championship fight in Saudi Arabia, multiple sources told ESPN on Friday.

The fight could take place on Dec. 23 or sometime in January, sources said. First, Fury must handle business without injury when he meets former UFC champion Francis Ngannou on Oct. 28 in Saudi Arabia on ESPN+ pay-per-view.

Fury-Usyk will crown boxing's first undisputed heavyweight champion in the four-belt era and is a rare meeting between heavyweights recognized as two of the best pound-for-pound in the world (Fury is No. 6; Usyk is No. 3.)

Fury, the WBC champion, and Usyk, who holds the WBA, IBF and WBO titles, were in talks to fight this past April at London's Wembley Stadium before negotiations collapsed at the 11th hour.

Usyk (21-0, 14 KOs) went on to fulfill his WBA mandatory defense with a ninth-round KO of England's Daniel Dubois in August in Wroclaw, Poland. The former undisputed cruiserweight champion captured the three heavyweight titles when he outpointed Anthony Joshua in September 2021.

Ukraine's Usyk, 36, defeated Joshua again in the August 2022 rematch. The Olympic gold medalist is ESPN's No. 2 heavyweight.

Fury (33-0-1, 24 KOs) is one of the biggest stars in global boxing. His Netflix reality show debuted this summer, and he has also appeared in WWE. Fury, 35, is gearing up for an Oct. 28 nontitle fight with Ngannou before he heads into the biggest showdown of his career, though Fury is no stranger to marquee fights.

"The Gypsy King" upset Wladimir Klitschko in 2015 to capture three heavyweight titles but never made a defense. Instead, he battled substance abuse and struggled with his mental health during a 2½-year layoff where he ballooned to over 400 pounds.

Fury made one of sport's best comebacks in 2018 with a pair of tune-up wins before he pushed Deontay Wilder to the brink in a draw for the WBC heavyweight title that December. Fury was floored twice by Wilder -- in the ninth and 12th round -- but miraculously beat the count in the final round to settle for a draw in a fight he appeared to win.

Fury left no doubt in the immediate rematch with a comprehensive beatdown of Wilder -- including a perforated ear drum -- that was stopped in Round 7 when Wilder's trainer threw in the towel.

Fury was slated to meet Anthony Joshua for the undisputed heavyweight championship in 2020 before an independent arbitrator ruled Fury owed Wilder a third fight because of the rematch clause. The trilogy bout ended up a heavyweight classic. Fury survived two knockdowns and scored three of his own to brutally conclude the rivalry in Round 11.

Fury-Wilder 3 was named ESPN's Fight of the Year and Knockout of the Year.

Fury went on to score inside-the-distance wins over fellow English fighters Dillian Whyte and Derek Chisora last year in London and now prepares for his toughest challenge yet.

Usyk is a crafty boxer who utilizes angles and excellent footwork to befuddle opponents. Fury, of course, is already an all-time great heavyweight who stands at 6-foot-9, 270 pounds. He can box off the back foot or with a swarming pressure style he unveiled in the Wilder rematch.