ATLANTIC CITY – David Tua is the hardest puncher on the planet, and proved it again last night – along with his worth as a heavyweight contender.

It took just 30 seconds and one thunderous right hand to send Michael Moorer to the Trump Taj Mahal canvas, and Tua to a possible title shot.

Their relationship has come full circle, like the looping right that floored Moorer in front of 4,741 at Mark G. Etess Arena. When Tua first met Moorer in 1992, Tua was a youngster learning from a contender. Last night he climbed over his friend’s limp body toward boxing’s pinnacle.

“I worked hard, and the hard work paid off,” said Tua (41-3, 36 KOs). “My strategy was to start at the body and go to the top. I put my will on him. I’m just glad it worked out great. I’ll fight anybody, but obviously I want a title shot.

“I respect Michael, but I didn’t see any southpaw in him. I just came out and did what I had to do. I’m a friend of Michael’s, and always will be. I just told him that’s the way it happens sometimes.”

So this is how a contender is born – or reborn. Whatever luster he’d lost from being dominated by Lennox Lewis in a 2000 WBC/IBF title fight and beaten by Chris Byrd last Aug. 18, Tua has regained. Could title shots against Lewis, John Ruiz or Wladimir Klitschko be next?

His domination of two-time former champion Moorer (43-3-1) was complete and convincing, too quick to cook minute rice or boot up a computer. Despite their friendship – they trained at the same Houston gym in ’92 – Tua took it to the savvy but overmatched 34-year-old Moorer.

Tua is a slow starter and has had trouble with lefties. But trainer Kevin Barry made sure he had a healthy sweat going, and when they saw Moorer come out bone dry, Barry told Tua attack.

Tua backed him into the corner with combinations to the body, and hooks as Moorer retreated. And while Moorer was wary of Tua’s vaunted left hook, the squat Samoan connected with a right to the chin that sent Moorer to the canvas. A left to the head on the way down left no doubt.

“He had long looping punches I couldn’t do anything about,” Moorer said. “But I know who I am. I’m going to go back into the gym and keep fighting.”

As Tua ran to the far corner, knelt and prayed, Moorer lay prone on the canvas for nearly a minute. Ref Rudy Battle could’ve counted to 30 before the Brooklyn-born Moorer – in his fifth fight after a three-year layoff – started to stir.