A rematch of the biggest box office bout in boxing history is under speculation, potentially putting the proposed Floyd Mayweather Jr.–Mike Tyson exhibition into doubt.

In their first fight, Mayweather faced Manny Pacquiao on May 2, 2015, at the MGM Grand in Las Vegas and won by unanimous decision with scores of 118–110, 116–112, and 116–112. The contest broke records in both revenue and pay-per-view sales and was billed as the “Fight of the Century.”

Talks are reportedly underway for Mayweather vs Pacquiao II, with April in Las Vegas identified as a possible date according to journalist Dan Rafael. It remains unclear whether the bout would be a professional contest or an exhibition.

Pacquiao said there have been discussions about a rematch, adding, “There is a talk. I’m happy to start talking about, discussing about a possible rematch with Floyd.” He also told the Ariel Helwani Show earlier this year, “I don’t want an exhibition, I want a real fight.”

Mayweather, who has not fought professionally since 2017 and has instead taken part in exhibition bouts, would need to return to full professional competition to face Pacquiao in a sanctioned contest.

If the rematch moves forward, the scheduled exhibition between Mayweather and Tyson would likely be postponed or cancelled to accommodate the negotiations.