Floyd Mayweather isn't just planning for another fight with Manny Pacquiao in a rematch of their record-setting 2015 welterweight title unification bout, he is planning for a tuneup fight first -- in Japan.

Mayweather, who has been on a trip to Japan, on Saturday announced that he was coming out of yet another retirement and that he and Pacquiao -- whom he met with while in Tokyo -- would meet again in December in a rematch. Mayweather won a clear unanimous decision over Pacquiao in their long-awaited 2015 showdown that set every economic record in combat sports, including selling 4.6 million pay-per-view subscriptions, but was a critical dud.

Pacquiao, a promotional free agent like Mayweather, backed up Mayweather's announcement, but there has been a change of plans. Instead of going directly to the rematch with Pacquiao, Mayweather, in a video posted on TMZ, said Wednesday that he is planning to fight another fight first.

"I know everybody heard about the Mayweather-Pacquiao fight, but before the Mayweather-Pacquiao rematch I will be back in Tokyo for a huge boxing event. Stay tuned," said Mayweather, who was wearing a baseball hat with "50-0" on the front to signify the record he retired with after knocking out UFC star Conor McGregor in the 10th round last August in the second-highest-grossing fight of all time. Mayweather had come out of retirement to fight McGregor, who crossed over to boxing from mixed martial arts for the bout.

Mayweather (50-0, 27 KOs), 41, of Las Vegas, did not mention a specific venue, opponent or date for his return fight, but if he fights another fight before facing Pacquiao again it means the rematch with Pacquiao wouldn't happen until at least next year.

Pacquiao (60-7-2, 39 KOs), 39, the Filipino legend and the only fighter in boxing history to win world titles in eight weight classes, returned from a one-year layoff on July 15 in Kuala Lumpur, Malaysia, to knock out Lucas Matthysse in the seventh round to win a secondary welterweight world title, after which he said he wanted to fight Mayweather again.

Pacquiao has had financial problems and owes tens of millions of dollar to the IRS despite the nine-figure payday he made against Mayweather in 2015, not to mention numerous other eight-figure paydays he had in his career. He has made it clear he wants the rematch with Mayweather.

"We cannot say when or exactly what date," Pacquiao told the Philippines' ABS-CBN News. "[Mayweather is] announcing his comeback from retirement. He wants to fight and challenge me; he wants to get my belt. Right now, we're negotiating and hoping to finalize that. I'm always available. I'm always available for him. It's important to [have the rematch], as we have unfinished business. We've been waiting for a long time."