By Darren Walton

Australia's world heavyweight boxing contender Alex Leapai has cut short an intense sparring session in Sydney as a precaution after straining his neck against giant Romanian Razvan Cojanu.

With Leapai's shot at becoming Australia's first heavyweight world champion in more than a century just a fortnight away, he was taking no chances and stopped after four rounds slugging it out with the 201cm tall Cojanu.

Leapai was planning to have a further two rounds on Thursday but will instead resume on Friday.

"It's just so close to the fight now, just any little niggles we've got to be spot on," he said.

"It's a little on the precaution side, but everything is spot on.

"We're back to the gym tomorrow to do some heavy sparring again, so everything is going good."

Cojanu, tipped as a future world heavyweight champion himself, was flown in by Leapai's camp specifically to serve as a giant copy of 198cm Ukrainian champion Wladimir Klitschko, who the Australian will fight in Germany on April 26 for the world title.

Leapai's trainer Noel Thornberry was delighted with the intensity and quality of his charge's work-out with the Romanian, but pulled him out of the ring to prevent aggravating his neck niggle.

Thornberry said Leapai would have physiotherapy, massage and possibly an ultrasound but was not concerned at all.

"When you get a strain or whatever it may be, they only get worse if you keep going," he said.

"It won't get better so we thought it's better to be safe than sorry.

"We don't see it as a problem. We'll see when he cools down, but everything is fine.

"These sort of things happen all the time."

Leapai, 34, is the first Australian in 106 years to challenge for a unified world heavyweight title.

He and Klitschko will fight for the WBA, IBF, WBO, IBO and The Ring Heavyweight Championship in Oberhausen, Germany.