Philippine boxing legend Manny Pacquiao says the outcome of his July bout against Argentine Lucas Matthysse will likely determine whether he will hang up his gloves after a storied career.
After a one-year hiatus from the ring, the 39-year-old has started training two weeks earlier than usual to bring himself up to peak fighting condition.
"I am not saying it will be the last, but it will be the basis for (me) to think about (whether) to continue or not," Pacquiao told AFP after training in Manila on Thursday.
"So I am trying my best and doing our best in the training in this fight to show if I can still do it or not," he added.
Pacquiao has won world titles across an unprecedented eight different weight classes, but critics - including Matthysse, who is four years his junior - question his ability to box at the top of his game due to his age.
The fighter, who won 38 of his first 47 professional fights by knockout, has not knocked out an opponent in nearly nine years.
The two will face off for the World Boxing Association welterweight belt on July 15 in Malaysia.
The fight comes a year since the southpaw lost his World Boxing Organization welterweight crown in a shock points defeat to Australia's Jeff Horn.
In contrast, Matthysse won the vacant WBA belt after beating Thailand's Teerachai Sithmorseng in January.
"(Matthysse) is a very aggressive fighter. I am not worried about his style. My worry is I need to get 100 percent conditioned - the stamina, the power and the strength to survive the 12 rounds," Pacquiao said.
However, the challenger predicted on Thursday that his fans would see him on top form in Malaysia.
"A young Manny Pacquiao throwing a lot of punches, and more footwork, head movements, side by side (motions) - that's my goal to achieve for this fight," he said.
Pacquiao, who is also a Philippine senator, previously rejected criticism that his recent losses have tarnished his record.
On Thursday he hit the mitts with friend and compatriot Restituto "Buboy" Fernandez whom he chose to be his head coach for the fight over long-standing US trainer Freddie Roach.
Roach expressed hurt last month after saying ties had been cut.
"Buboy adapted the style of Freddie Roach and he knows what to do for this training so I am confident with Buboy," Pacquiao said, refusing to compare the two trainers.