Manny Pacquiao admitted he was "50-50" about retirement after bidding farewell to boxing Saturday with a vintage performance to defeat long-time rival Tim Bradley.

The 37-year-old had promised to deliver an explosive display and did not disappoint 14 665 fans who had crammed into the MGM Grand Garden Arena to catch what may have been the final curtain call of an icon.

Pacquiao, the only man to capture world titles in eight different weight divisions, produced flashes of brilliance and knocked down Bradley twice on his way to a unanimous decision in the welterweight duel.

It was the sort of performance his admirers believe could persuade him to prolong a career that has earned him more than $500 million over 21 years.

A smiling Pacquiao later appeared before reporters and admitted that while he was conflicted about quitting the ring, his decision – for now – was to spend more time with his family before concentrating on his political career in the Philippines.

Asked if he might best serve his homeland by continuing to fight, Pacquiao said he had promised his family he would retire.

"Let me enjoy first a retired life," he said. "I'm not there yet, so I don't know what it feels like. But I made a commitment to my family. I made my decision."

Invited to make a definitive declaration of retirement, Pacquiao smiled.

"My heart is 50-50," he said. "But I love my family, I honour my family, my kids... right now, my decision is to retire."

Pacquiao, whose last outing was his ill-fated "Fight of the Century" against Floyd Mayweather last May, clearly relished his return to the ring after an 11-month layoff, smiling throughout his third battle with Bradley.

"I felt fresh, every round, it was exciting – I felt like I did when I started first boxing here in America in 2001," Pacquiao said. "If you ask me about my condition, my body – my body feels okay, I can still give 100 percent, training."