Manny Pacquiao says a rematch with Floyd Mayweather is a "big possibility" as he "cannot retire with peace of mind" following his 2015 defeat.
The Philippine great lost to American Mayweather in Las Vegas by unanimous points decision, although he has since regained a version of the world title.
The two met in Japan at a concert, where they talked about a rematch.
"I told him 'I've got the belt and I am a champion' and he said he would get my belt," Pacquiao said.
The 2015 fight between the two multi-weight world champions was billed as the 'Fight of the Century,' but following a tame defeat, which saw Mayweather add the WBO welterweight title to his WBC and WBA titles, Pacquiao said he had been suffering with a shoulder injury.
"It's different - this time there are no excuses," Pacquiao, 39, told BBC Radio 5 live boxing correspondent Mike Costello.
"I cannot retire with peace of mind with that defeat."
In January, Pacquiao will defend his WBA world welterweight title against American Adrien Broner, himself a four-weight world champion. The belt is a secondary title, as the holder of the 'super' title, Keith Thurman, is recognised as the champion of the division by the WBA.
Pacquiao, who also said he would be "happy" to take on British fighter Amir Khan, added: "We met in Japan - we met accidentally. He said he wants to have a rematch and we agreed, but not this time, maybe after the January fight."
Mayweather, 41, has not fought since he beat Irish mixed martial artist Conor McGregor in 2017, but will make a return to the sport on New Year's Eve against Japanese kick boxer Tenshin Nasukawa.
Mayweather posted about the encounter with Pacquiao on Instagram. "Another nine-figure pay day on the way," was the American's assessment.