Newcastle skipper Jarrod Mullen doesn't believe the controversy swirling around the Sydney Roosters will be a distraction for the minor premiers in Saturday's NRL grand final qualifier.

Reports emerged on Wednesday that six players returned elevated readings for Human Growth Hormones from blood tests carried out by sports nutrition company Nubodi.

The results of at least three players - Sam Moa, Boyd Cordner and Roger Tuivasa-Sheck - were said to have been found on the phone of an alleged organised crime figure.

The trio were later re-tested by the Roosters and did not return elevated levels of HGH, according to the club.

The Roosters, who advised the NRL's integrity unit of the matter earlier this year and have not been contacted by ASADA as a result, later severed ties with Nubodi - who it had initially hired to help finetune detox diets for players.

While the revelations have dominated news headlines in the lead up to Saturday's preliminary final, Mullen said he didn't think the off-field drama would play any role in the do-or-die match.

"I don't think (it will) at all," he told reporters on Friday.

"They'll be ready to play. They're the minor premiers.

"They've got a great team, so they'll be coming hard to play."

Regardless, the veteran five-eighth said the Roosters will be the one under the most pressure to perform.

"They're the red-hot favourites going in," he said.

"We're going in as the underdogs and that's the way we like it.

"No-one expected us to win the first round (of finals against Canterbury) and definitely no-one expected to win last round (against Melbourne).

"So it's good. The team's building confidence going into tomorrow night so it should make for a good match."

Mullen puts most of that extra confidence down to the experience of supercoach Wayne Bennett - even after he refused to give a guarantee earlier in the week that he will see out the remaining two years of his contract at the Knights.

"Wayne's been pretty up front with everyone, so everything's all sweet there," he said.

Despite being named on the wing James McManus won't be playing on Saturday night thanks to a persistent knee injury that has cruelled the back end of his season.

"Jimmy's out and obviously he's shattered," Mullen said.

"He's been one of our best players all year.

"With Kevin Naiqama coming in, he did a great job for us last week and he'll fill the position well."