Knights star Kalyn Ponga is in doubt for Origin I after being ruled out of Sunday's clash against Manly

His much-anticipated return from injury and showdown with dynamic fullback rival Tom Trbojevic is on hold after he failed to fully recover from the slight groin tear that has kept him out of Newcastle's past two matches.

It remains to be seen what that means to his hopes of playing for Queensland in 11 days time in the Origin series opener in either Melbourne or Townsville.

There is a suggestion he might still be named in the Maroons squad when it is announced on Monday and given time to prove his fitness. But it will be a big ask to play in one of the biggest games of the season having not played any football for more than a month and after hardly training during that period.

Knights coach Adam O'Brien told the Newcastle Herald yesterday the club was not prepared to risk Ponga against the Sea Eagles but would not speculate on his chances of fully recovering in time for Origin.

"KP [Ponga] won't be playing unfortunately - he is still not quite right and we are not taking any chances so we'll be going in against Manly without him," O'Brien said.

Asked about his fullback's Origin chances, O'Brien said: "That will be a matter for KP and the Maroons to sort out. We won't be interfering in that."

There is little doubt Ponga will be desperate to play after missing the entire 2020 series at the end of last season after going in for major shoulder surgery.

O'Brien indicated Tex Hoy will come into the team as Ponga's replacement at fullback against Manly.

In brighter news for the Knights, who will go in against Manly as big underdogs at home, centre Bradman Best, who missed last weekend's loss to the Cowboys in Townsville with tightness in his hamstring, is a certain starter.

"Bradman's been running freely and there is no issues with him," O'Brien said.

"Hopefully, we can get through captain's run unscathed and get ourselves ready to go into battle and fight hard."

O'Brien admitted defence has been a big focus for his side in the build-up to the game with the Trbojevic threat from fullback high on the priority list.

"We've definitely had some things to fix up on our edges defensively and we've worked hard all week on that," he said.

Manly were lethal against Parramatta out wide last weekend and had a lot of success going at the Eels' right edge defence.

It's an area the Knights expect them to heavily target again given Newcastle has leaked more tries there than any other side this season.

"It's fair to say our right edge has been a focus for us to make sure we are sound defensively," O'Brien said.

Asked if he will stick solid with his centre/wing combination of Enari Tuala and Starford To'a or give rookie Simi Sasagi another opportunity following his debut against the Cowboys, O'Brien was giving little away: "Enari and Star have probably spent the most time standing beside each other out there but Simi offers another attacking dimension. We'll make a final call on it during captain's run and go from there."

O'Brien admits Trbojevic's return has transformed Manly.

"Tom seems to make everyone around him seem a little bit faster and a whole lot more confident," he said.

"We need to make sure we are on the ball all across the field because he'll hurt you from his own end, he'll hurt you in and around the ruck if you are lazy defensively but he's also got plenty of skill.

"You can't just go in there looking to jam on him because he can pass but if you are passive, he can beat you with pace.

"They have some good variation with their attack - it's not just one dimensional, he pops up in a lot of different shapes. There will definitely be some high alert around where Tom is."

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