Manny Pacquiao "has more quality fights left in him" if he opts against retiring from boxing, according to trainer Freddie Roach.
Pacquiao takes on Timothy Bradley in Las Vegas on Saturday in what is expected to be his final bout before quitting to focus on political ambitions in his native Philippines.
But while Roach concedes his fighter looks to be readying himself to bow out, he is also optimistic about a future in the ring.
"I personally don't know if this will be Manny's last fight, but he is training like it's going to be his last fight," he said. "Manny has achieved so much in his boxing career and, if this is going to be his swansong, I know he wants to go out blazing with a spectacular performance.
"If the opportunity for a knockout presents itself during the fight, he's going to go for it. He knows how to close the show and he wants this show closed with fireworks. He wants to finish the book on his boxing career with a spectacular ending.
"I do think Manny has more quality fights in him. His power, speed, work ethic are still superior to most others."
And Roach, who has worked with the likes of Mike Tyson, Miguel Cotto and Oscar De La Hoya, claims Pacquiao is the strongest fighter he has trained.
"Manny is the greatest fighter I have ever worked with," he added. "I have never seen another fighter accomplish so much. Forget the raw talent and drive to win, Manny was a great student who never rested on his laurels.
"He was a sponge who was always willing to learn new things. He challenged me to teach him new things. He made me a better trainer.
"For me, it's been an experience unique to Manny. I wish I had a million fighters with as much drive and a willingness to learn new things."