In an unexpected move, super middleweight contender Callum Smith has joined the World Boxing Super Series super middleweight tournament rather than press for his mandatory world title shot.

Organizers announced Thursday that England's Smith has become the fifth fighter to join the 168-pound field.

Smith (22-0, 17 KOs), 27, had signed to fight former titlist Anthony Dirrell (30-1-1, 24 KOs) for the belt vacated in January by Badou Jack, who is moving up to the light heavyweight division. They were supposed to meet Sept. 9 in Los Angeles. However, Smith promoter Eddie Hearn of Matchroom Boxing said Dirrell breached the agreement when his team tried to have the fight moved to a different date in Dirrell's hometown of Flint, Michigan.

There was an attempt made to have Dirrell added to the tournament as well and to have their bout as one of the quarterfinal matches, but Dirrell declined to join the field, according to the World Boxing Super Series. So that leaves Smith to instead fight for the WBC's symbolic diamond belt in the tournament rather than an actual world title.

"It's been a very frustrating period for Callum, but now we have clarity and something he can really get his teeth into," Hearn said in a news release. "He is a technically excellent fighter with huge power who we believe has all the attributes to become a world champion -- and stay there."

Smith joins a tournament field that also includes countrymen George Groves (26-3, 19 KOs), who holds one of the super middleweight world titles, and Jamie Cox (23-0, 12 KOs) along with former world titleholder Juergen Braehmer (48-3, 35 KOs), of Germany, and Sweden's Erik Skoglund (26-0, 12 KOs).

The final three participants are expected to be announced Friday. A source with knowledge of who they are told ESPN that Turkish contender Avni Yildirim (16-0, 10 KOs), rising contender Rob Brant (22-0, 15 KOs), of St. Paul, Minnesota, and the winner of the fight between England's Chris Eubank (24-1, 19 KOs) and former world titleholder Arthur Abraham (46-5, 30 KOs) of Germany, who meet July 15 in London, will round out the field.

Callum Smith will compete in the World Boxing Super Series, choosing the eight-man tournament over a fight for a vacant world title. Dave Thompson/Getty Images

Smith said he was happy to join the tournament even if he won't get a shot at a world title next.

"I am thrilled to participate in the World Boxing Super Series, the Champions League of boxing," Smith said in the news release. "What an honor it will be to fight for the WBC diamond championship in the quarterfinal. But there is so much more at stake than just one belt -- the Muhammad Ali Trophy as well as a potential domestic showdown with George Groves in the final.

"This tournament is very exciting for boxing, and I am thrilled to be a part of it. I look forward to travelling to Monaco for the draft gala on Saturday and find out who my opponent will be."

In March, Comosa AG announced plans for two eight-man, single-elimination tournaments in which 16 fighters will divvy up $50 million in prize money, with the winner of each tournament also receiving the Muhammad Ali Trophy. Comosa AG enlisted promoters Richard Schaefer and Kalle Sauerland to promote the cards and decided that the first two tournaments will take place in the cruiserweight and super middleweight divisions.

The tournaments are supposed to kick off in September with quarterfinal matches in each weight class. The semifinals are scheduled for early 2018 and the finals in May 2018. The draw for each tournament will take place Saturday in Monte Carlo, Monaco, with the top four seeds -- which are to be determined -- in each field selecting their quarterfinal opponent from the remaining unseeded fighters. The draft will streamed live at WorldBoxingSuperSeries.com beginning at 5 p.m. ET.

"Smith has been one of the hottest prospects in the U.K. for years, and now he gets his chance to showcase his talents on the biggest stage of all," Sauerland said. "The super middleweight tournament will be exceptional, and we will announce further high-profile names very soon."

Seven fighters in the cruiserweight field have been announced, and they are a who's who of the 200-pound weight class, including four world titleholders -- Oleksandr Usyk (12-0, 10 KOs), Yunier Dorticos (21-0, 20 KOs), Murat Gassiev (24-0, 17 KOs) and Mairis Briedis (22-0, 18 KOs) -- along with former titleholders Krzysztof Wlodarczyk (53-3-1, 37 KOs) and Marco Huck (40-4-1, 27 KOs) and the "Russian Hammer," Dmitry Kudryashov (21-1, 21 KOs), a top contender.

The final fighter for the cruiserweight tournament will also be announced Friday. It was expected to be Krzysztof Glowacki (27-1, 17 KOs), a former world titleholder from Poland, but he will instead serve as an alternate with Mike Perez (22-2-1, 14 KOs), a Cuban defector fighting out of Ireland, landing the final slot, according to a source with knowledge of the deal.

Perez, a onetime heavyweight contender, returned from a 25-month layoff on June 10 as he dropped 42 pounds to fight as a cruiserweight and scored a first-round knockout of Viktor Biscak.