Four-weight world champion Saul ‘Canelo’ Alvarez is suing streaming service DAZN and promoter Oscar de la Hoya for at least $280m (£216m).
Papers filed with the US district court in California state the Mexican is suing for “breach of the single largest contract in the history of boxing”.
In 2018, Alvarez signed a $365m (£282m) deal for 11 fights on DAZN.
Alvarez’s claim details 11 complaints, including breach of contract, negligent interference and fraud.
The legal papers – seen by BBC Sport – request a jury trial and state DAZN and De la Hoya’s Golden Boy Promotions organisation have “broken the promises they made to each other, Alvarez, and boxing fans”.
At the time of Alvarez signing his fight contract, those close to the deal said it was one of the most lucrative not only in boxing but in all of sport.
The court documents state that after the first of his 11 fights was completed, DAZN would pay Golden Boy Promotions $40m for each of the remaining 10 bouts and $35m would be passed on to the fighter on each occasion.
Three of the 11 contests have now taken place but with no agreement reached for a fourth, 30-year-old Alvarez claims DAZN replied to a letter sent by his team in June stating the $40m fee would not be paid to Golden Boy Promotions for his next contest.
This alleged lack of payment has prompted him to sue both parties for breach of his contract and he wants “at least $280m” in damages.
The case filings claim that DAZN cited the fact Alvarez had not fought Gennady Golovkin in 2019 as one of the factors in their decision to not pay him for his next bout.
According to the legal documents, they eventually offered to pay “a fraction” of his contracted fee and Alvarez claims his original agreement “did not mention that DAZN would have any right to accept or reject any opponents”.
He claims Golden Boy Promotions made promises or representations regarding opponents to DAZN that he was unaware of and that were inconsistent with the contract he signed.
As a result, a fraud-concealment complaint is filed against Golden Boy Promotions, who Alvarez has worked with since 2010.
The identity of Alvarez’s next opponent is an ongoing story within boxing.
The likes of Britain’s WBA world super-middleweight champion Callum Smith and WBO world super-middleweight title holder Billy Joe Saunders had been heavily linked with facing him.
Alvarez has lost once in 56 fights since turning professional in 2005.
BBC Sport has contacted Golden Boy Promotions and DAZN for comment.
US media quote a Golden Boy Promotions spokesman stating no-one from the organisation “ever promised anyone that Canelo would fight any specified opponent”.
Golden Boy Promotions’ statement added that DAZN are refusing to honour Alvarez’s contract “by not approving the outstanding opponents we have presented to them and by refusing to pay the contractually required amount”.