Williams' return date will be determined by weekly scans on his torn lung, but he has backed replacement half Mitch Cornish to help carry on Canberra's winning momentum.

Cornish, 22, is playing for his NRL future. The Raiders have signed Gold Coast half Aidan Sezer for 2016, leaving off-contract Cornish in limbo as clubs battle for a number of key playmakers still on the market.

The Raiders dropped Cornish to NSW Cup after a slow start to 2015, Williams coming in and helping steer Canberra to four wins from their past five matches.

But Williams, who has fought his way back into the NRL after stints in NSW Cup and the UK Super League, backed Cornish to rebound.

"I think he'll be better for it," Williams said. "It's not the end of the world going back to reserve grade. He's a great young footballer, he's kept a good attitude and there's no reason why he won't come back and do a really good job.

"I'm sure he'll want to go out there and make an impact, but [Raiders coach Ricky Stuart] won't complicate things for him too much. He's just got to come in and do his job, that's all the team needs."

Williams is hoping to return to training as early as next week, but counts himself "lucky" after initially dismissing his bizarre injury as bruised ribs and flu symptoms.

Williams spent Saturday night in hospital after suffering the collapsed lung, but said he didn't realise the extent of the injury until after Canberra's 56-16 win over the Titans.

Williams was winded when giant Gold Coast forward Ryan James fell on top of him after challenging a kick about 20 minutes into the match. But Williams had slightly cracked a rib and his right lung had started to collapse because of the force of weight.

eammates have praised his courage for playing on, including scoring the final try, but Williams said he didn't feel it was brave.