Timothy Bradley says he is not about to let the chance of a lifetime pass him by when he steps into the ring against Filipino fight king Manny Pacquiao in Las Vegas, this weekend.

“It’s all or nothing,” Bradley vowed.

“No rounds off. Round by round, I have to win each one.”

Bradley, 28, is unbeaten in 28 fights. But he has never fought anyone of Pacquiao’s stature and his record includes just 12 knockouts.

He’ll be fighting for just the ­second time at 147 pounds, moving up to challenge for Pacquiao’s World Boxing Organisation ­welterweight belt.

Pacquiao trainer Freddie Roach says he doesn’t believe Bradley has the speed or power to beat his fighter.

Roach questions the wisdom of Bradley’s vegan diet – a rarity in the boxing world – and says the Californian’s muscular physique could be a hindrance rather than an asset.

Bradley acknowledges the highly-publicised bout is a step up for him, but says the years of paying his dues fighting in club venues have given him the versatility to adapt to whatever Pacquiao will present.

“I came from the lumberjack yards, fighting in little ballrooms to reach this point.

“Now we’re in Las Vegas... it’s the place to be and we’re going to be fighting in front of thousands of spectators,” said Bradley, who once waited tables to support himself as he tried to establish his ring career.