Anthony Joshua and Deontay Wilder will compete in separate bouts on Dec. 23 in Riyadh, Saudi Arabia, sources told ESPN, in what could serve as a prelude to the long-awaited battle between the former heavyweight champions next year.

Joshua will fight Otto Wallin, who gave Tyson Fury all he could handle during their 2019 meeting, while Wilder will take on former heavyweight titleholder Joseph Parker, sources told ESPN on Tuesday.

If both Joshua and Wilder come away with victories, they'll be on a collision course for a much-discussed fight between two of the division's bigger punchers. Wilder is considered by many the most devastating puncher in heavyweight championship history.

On the undercard, Dmitry Bivol will defend his WBA light heavyweight title against Lyndon Arthur, per sources.

The matchup will be Bivol's lone bout of 2023. The Russian boxer was named ESPN's Fighter of the Year for 2022 following wins over Canelo Alvarez and Gilberto Ramirez.

Sources also told ESPN that heavyweights Daniel Dubois and Jarrell "Big Baby" Miller will square off, as will fellow big men Frank Sanchez and Junior Fa. Cruiserweight champion Jai Opetaia, ESPN's No. 1 200-pounder, will also compete on the star-studded card, sources added.

Fury and Oleksandr Usyk were slated to meet for the undisputed heavyweight championship on Dec. 23 in Saudi Arabia's capital, but after Fury's tougher-than-expected win over former UFC heavyweight champion Francis Ngannou, the bout was moved to Feb. 17 in Riyadh, sources said.

That left Dec. 23 open, and Saudi officials moved quickly to put together a stacked card featuring the third- and fourth-best heavyweights in the division, along with other contenders in boxing's glamour division.

Joshua (29-3, 23 KOs) is ESPN's No. 4 heavyweight. The two-time heavyweight champion from England has scored two victories since he suffered back-to-back losses to Usyk, and in the process, his three titles.

Most recently, Joshua scored a seventh-round KO of Robert Helenius in August. The 34-year-old also lost to Andy Ruiz Jr. in June 2019, but rebounded to defeat him later that year in Riyadh to reclaim the unified championship.

Wilder (43-2-1, 42 KOs) has fought only once since he suffered an 11th-round KO loss to Fury in their heavyweight title trilogy in November 2021, which was named ESPN Fight of the Year and KO of the Year.

And that return bout lasted only one round as Wilder separated Helenius from his senses last October. The 38-year-old from Alabama drew with Fury in the first bout before he was also stopped in the rematch. However, Wilder floored Fury four times between the first and third meetings.

Sweden's Wallin (26-1, 14 KOs) pushed Fury to the brink when they fought in 2019. Wallin, ESPN's No. 10 heavyweight, is coming off a career-best win, a split-decision victory over former cruiserweight titleholder Murat Gassiev in September.

Filip Hrgovic, ESPN's No. 7 heavyweight, will also appear on the card, per sources. Croatia's Hrgovic (16-0, 13 KOs) is No. 1 in the IBF's heavyweight rankings while Wallin is No. 2. Fury-Usyk has a two-way rematch clause, and it's overwhelmingly likely that they'll meet again later next year. If so, the IBF has already ruled that Hrgovic would then fight the next available contender for the vacant title.

That's currently Wallin, with Joshua one spot behind him, meaning the winner of the bout could be positioned for a title fight vs. Hrgovic.

New Zealand's Parker (33-3, 23 KOs) is ESPN's No. 8 heavyweight. He defeated Ruiz via majority decision in 2016 to pick up a vacant heavyweight title but lost it three fights later to Joshua. Parker has scored three consecutive wins since an 11th-round KO loss to Joe Joyce last year.

Bivol, 32, is ESPN's No. 4 pound-for-pound boxer. Bivol (21-0, 11 KOs) underwent hand surgery earlier this year, sources said.

Arthur (23-1, 16 KOs), from England, is ESPN's No. 9 light heavyweight. The 32-year-old's lone defeat came via fourth-round KO to Anthony Yarde in a 2021 rematch. Arthur defeated Yarde via split decision when they met one year earlier.

England's Dubois (19-2, 18 KOs) was knocked out in Round 9 of his heavyweight title challenge of Usyk in August. Brooklyn's Miller (26-0-1, 22 KOs) was set to fight Joshua in 2019 before he was suspended for PED use. Miller was later suspended again for the same infraction.

Cuba's Sanchez (23-0, 16 KOs) is one of the most-avoided fighters in the heavyweight division. He's trained by Eddy Reynoso, the former ESPN Trainer of the Year and Canelo Alvarez's coach.

New Zealand's Fa (20-2, 11 KOs) rebounded with a first-round KO victory last October. That ended a two-fight skid that included a decision defeat to Parker and a first-round KO loss to Lucas Browne.