The producer of two upcoming Floyd Mayweather fights filed a lawsuit in federal court Thursday, suing the star boxer for breach of contract while also attempting to stop his June 27 fight against Mike Zambidis next weekend in Greece, according to court records.
CSI Sports Events alleges in the suit that Mayweather breached his contract with the company when he agreed to fight Zambidis. CSI was contracted to produce Mayweather's exhibition fight against Mike Tyson as well as his professional bout against Manny Pacquiao later this year.
The suit, filed in the Southern District of New York on Thursday, asked the court to place a permanent injunction on Mayweather's fight against Zambidis because it breaches Mayweather's CSI deal. Judd Burstein, the attorney for CSI, told ESPN that he plans to file an emergency injunction application in federal court to try to stop the fight.
CSI is asking for $6.65 million in restitution from Mayweather and Frist Apex Ventures, the co-defendant in the case that CSI said acted as Mayweather's representative.
Messages left with Mayweather's representation were not immediately returned to ESPN.
The suit claims CSI and Frist Apex agreed to a deal on Aug. 10, 2025, for a Tyson-Mayweather fight that would take place in the spring of 2026. The suit claims Frist Apex had the authority to enter the deal on Mayweather's behalf. In a separate civil case, Mayweather is suing Frist Apex for aiding and abetting breach of fiduciary duty.
The CSI suit claims it agreed to pay Mayweather $14 million to fight Tyson, including a $2 million advance. According to the suit, the parties then signed a separate exclusive agreement in November 2025 for his fight after Tyson, where Mayweather would receive $35 million if Pacquiao was the opponent and 20% of any pay-per-view revenue. If the fight ended up not on PPV, Mayweather would receive "a $50 million buyout." If Pacquiao were unavailable, Mayweather would fight a different opponent for $20 million, along with other bonuses.
The suit then alleges Mayweather refused to tweet an announcement of his return to boxing in November 2025 -- through his then-business manager, Jona Rechnitz -- because "he was in the process of selling those very same rights to a third party."
CSI claims Mayweather entered into an agreement in December 2025 with another company, EverWonder, for the Pacquiao fight on Netflix for $24.75 million, including a $2.75 million advance and the potential for a $3.75 million bonus.
CSI and EverWonder then began working out a solution to the potential Mayweather-Pacquiao fight, according to the suit.
"We were prepared to go forward," Burstein said. "Tyson would go first, and CSI would allow, Pacquiao was going to go forward in the fall in the Sphere televised by Netflix with CSI getting full billing rights."
As part of CSI's deal with EverWonder, Frist Apex needed to repay an advance and Mayweather agreed to give CSI exclusive rights to the fight after Pacquiao, Burstein said. Frist Apex never repaid the advance, Burstein said.
As EverWonder negotiations took place, the suit claims CSI learned about a third fight agreement for Mayweather-Zambidis. The suit claims the Zambidis fight "would violate" CSI's exclusive rights with Mayweather.
The suit claims Mayweather then changed business managers from Rechnitz to Walter Jordon and that Jordon told CSI the Tyson fight would occur before the Zambidis fight. Mayweather then went through medical testing for the Tyson fight, according to the suit, and then asked for $150,000 in cash, which Burstein said CSI paid and that Mayweather signed the receipt.
The following day, the suit alleges, Mayweather announced he was fighting Zambidis despite CSI not agreeing to let that fight occur, Burstein said. In May, Tyson announced that he injured his hand and the scheduled May 30 fight needed to be postponed. The contract allowed for a six-month timeframe to reschedule the Tyson fight before an interim fight would be allowed. This also made the Zambidis fight Mayweather's return fight, which would also allegedly violate agreements with CSI.
The suit claims Mayweather attempted to terminate his contract with CSI on June 9 after he allegedly had breached his contract.
The CSI lawsuit is the latest in a litany of legal issues for Mayweather. He faces two felony charges for allegedly writing a bad check for a $200,000 watch in Las Vegas and has civil suits against him in four states with varying allegations, including nonpayment for goods and services. He also has a $7.2 million IRS lien against him for unpaid taxes.
As a plaintiff, Mayweather is suing Showtime, which used to televise his fights, for $340 million along with the suit against Rechnitz and Fritz Apex for $175 million, alleging fraud and aiding and abetting breach of fiduciary duty in both cases.