Manny Pacquiao intends to make sure it is a "clear decision" over the winner if, as planned, he faces former foe Floyd Mayweather Jr next year.

The rivals first met in the ring in May 2015, with Mayweather triumphing by unanimous decision on the scorecards following a long-anticipated bout that failed to live up to the hype.

Any possibility of a rematch seemed to disappear when Mayweather announced his retirement following victory over Conor McGregor in August 2017, leaving his professional record at 50-0.

However, the American is set to make a fighting comeback, announcing in Tokyo on Monday that he will face Japanese kickboxer Tenshin Nasukawa on December 31.

Pacquiao defeated Lucas Matthysse in July and is scheduled to be in action again on January 19 against Adrien Broner, yet is already looking ahead to the chance to settle an old score in 2019.

The Filipino fighter was bothered by a shoulder injury in the first clash with Mayweather but is determined to triumph convincingly second time around.

"There is a big possibility [in the rematch] because Floyd is coming back to boxing," Pacquiao told Sky Sports.

"He's fighting in December and I’m fighting in January, so there’s a big possibility for next year. After that, we are going to discuss a rematch.

"My thinking is to have the rematch and to make it a clear decision over who wins the fight. The last one we had, it was not clear who won. He didn't throw a lot of punches, but won the fight.

"I had a shoulder injury, but if there's a rematch there is no excuses."