Fighting on the Jeff Fenech-Azumah Nelson undercard at Melbourne’s Vodafone Arena, Whitehead knocked out opponent Justin Bailey in the third round.

It was Whitehead’s first bout since March last year and the 37-year-old’s first since turning professional.

Fighting in the heavyweight class, Whitehead floored Bailey in the first round before delivering the knockout blow in the third.

"Justin has got devastating body shots and he hurt Bailey with his big rights," Whitehead’s trainer, Barry Quinlan, said yesterday.

"Bailey was in really good nick and well prepared for the fight, but he just couldn’t handle Justin’s power.

"Bailey did a really good job to last as long as he did."

Whitehead had battled a bout of gastro in the lead-up to Tuesday night, but yesterday said he was rapt to have begun his professional career with a first-up victory.

"It was good that all the I work I had done in the lead-up paid off," Whitehead said.

"It’s just good to get a win on the board in front of a few people."

Also fighting on the Fenech-Nelson undercard was Ben Costello, formerly of Bendigo, but now based in Echuca.

Competing in a light welterweight bout, Costello, also making his professional debut, was beaten by South Australia’s Robbie "The Sandman" Sanders on a points decision.

Costello won the first of the four rounds against Sanders.

"I think with a lot of the hype being his first professional fight on a high-profile night probably added a lot of mental stress Ben wasn’t used to," Quinlan said.

"As a trainer you do your best to try to prepare them, but it probably takes three or four fights to adjust to (fighting on big cards).

"But it was a tremendous effort for Ben to go for the four rounds in his first fight."

Whitehead and Costello’s next fights could be as early as in three weeks’ time.