Ryan Papenhuyzen has conceded a return in round one is highly unlikely as the Melbourne superstar undergoes treatment in the US for his devastating knee injury.

The Storm fullback is in Philadelphia working with world renowned strength and conditioning specialist Bill Knowles, who has helped the likes of Tiger Woods and Andy Murray as well as fellow NRL gun Latrell Mitchell with his troublesome hamstring.

Still unable to run after his kneecap was shattered in a tackle back in July, Papenhuyzen said Knowles had boosted his confidence about being able to return to peak form.

He has posted videos on social media of pool sessions with Knowles, who Papenhuyzen said liked to "think laterally".

"It's been a bit of a discovery," Papenhuyzen told SEN on Thursday.

"I tried to come in without much expectation and I've already learnt so much ... if you looked at the notes on my phone, I don't think you could write more.

"It's a lot of information to retain but I'm feeling better personally and the leg is feeling better which is most important.

"It's very rewarding and fills you with a lot of confidence."

The 24-year-old said planned to do a proper pre-season to ensure he was at his best when he was finally ready to play.

That timeline means an improbable comeback for Melbourne's season-opener against grand finalists Parramatta on March 2.

"I don't really have a date in mind, it's about getting back to a level where I feel I can perform well again and once we're there, then we will start looking at dates," Papenhuyzen said.

"The thing that really resonated with me here is that I want to come back and perform, not just come back.

"That's what he's really highlighted, which is, 'You'll come back, no doubt about it, but there's a difference between coming back and coming back performing'.

"I think we just sort of cleared out a way of figuring that out and not being pressured by outside noise and sticking to our reconditioning process."

After sitting out a large chunk of 2021 due to concussion, he said that last year he suffered an ankle injury in the pre-season but pushed to play which then led to other issues before the knee blow.

"Looking back at that I didn't really get a pre-season in and then I came back and got injured, came back and got injured again," he said.

"That's what I've learnt over here now, that proof that you do need a good training block.

"You don't come back when you're ready to come back, you come back when you're ready to perform."