But as his journey from the NRL to the NFL continues to gather momentum, Hayne has showed off his amazing body transformation after six months of intense training in the United States that looks set to culminate in his position in the 49ers' final 53-man roster.

Just over five months ago, a few days after Hayne announced his deal with the San Francisco 49ers, the franchise's superstar quarterback Colin Kaepernick posted a photo of eight players at the EXOS training facility in Arizona, including Hayne.

They had ripped arms and chiselled abs – well, at least seven of them did.

Hayne, a renowned gym non-enthusiast in his days in the blue and gold of Parramatta, looked out of place in the company of such physiques, despite possessing a body that would have made most NRL players happy to stare in the mirror.

There had always been doubters, however this photo only added to the sceptics.

But as the rookie class of 2015 celebrated the end of pre-season in the 49ers locker room after Thursday night's victory against the San Diego Chargers, Hayne's body transformation was there for all to see.

He too, now, had those chiselled abs.

He too, now, had those ripped arms.

Now, the doubters have turned to believers. And the believers are multiplying by the minute.

Never before has Hayne looked so physically intimidating.

And it showed in the way he bumped off Chargers cornerback Lowell Rose in a highlight reel play that has since become a YouTube sensation with over 70,000 views inside the first 16 hours of its publication.

"This is by far the most he's looked after his body," Eels captain Tim Mannah told Fairfax Media.

"People were quick to judge him when they saw a photo of his body in the off-season. But he's got talent. You can have the best body in the world, but if you haven't got the skill there's no point having the body."

His best friend Krisnan Inu said Hayne was always "rubbish" in the gym, spending more time stretching than lifting weights.

But as Mannah explains, Hayne never felt the need to spend a lot of time pumping iron because of his ability to understand what his body needed to perform at its peak.

"He always had the talent, so back home he didn't have to push himself to be a freak," Mannah said.

"It came natural to him. I've never seen someone so in tune with their body. Trainers would get frustrated with him, but he knew what he had to do to be at his best come game day. It wasn't that he was lazy, he just didn't see the purpose of doing things he thought were not needed."