Penrith will welcome back attacking lynchpins Isaah Yeo and Api Koroisau in next Saturday's crunch clash against the resurgent Roosters.

But it is the defensive lapses on show in their second-rate 37-10 loss to Melbourne that have coach Ivan Cleary on edge.

The Panthers enjoyed a healthy share of first half possession in their grand final rematch but couldn't score a point until the final few minutes as the Storm ran roughshod.

Missing NSW Origin stars and Kiwi prop James Fisher-Harris always made the Sunday showdown a tall order, with Yeo (concussion) and Koroisau (suspension) returning to ease an injury-ravaged roster.

Mid-season pick-up Tevita Pangai jnr also begins training this week and is set to make his club debut against the Roosters, who are once again in top-four contention despite their own injury woes.

Cleary said son Nathan could play at this point in his shoulder injury recovery "if we were playing semi-finals".

Match Highlights: Storm v Panthers

But given the regular season has five weeks remaining, the star halfback will likely be kept on ice as Yeo and Koroisau offer much-needed reinforcements around the ruck.

"We get Api Korosiau back next week, Isaah Yeo will be back next week and we'll get Tevita Pangai as well," Cleary said.

"That'll be a nice little inclusion for the team.

"[Cleary] is coming along well. I don't have a date yet.

Cavalry coming, but Cleary unlikely to face Roosters

"But we want him to come back not just to play but we want him to be able to play at his best. There's no need to rush him along.

"When he comes back there will be no doubt about it, he'll be ready.

"Of course you'd like to have your best players. We've certainly got a few gears left in us when we get everyone back. Throughout the night [against Melbourne] our defensive resolve wasn't good enough.

"Maybe having those players out did a little bit to their mindset, I'm not sure, but I'd certainly expect a bit better than that."

Penrith's concerning defence against the NRL frontrunners followed last week's scraping past the Broncos with 69 missed tackles, with Cleary lamenting the lack of scrambling efforts to keep the Storm in check.

"I don’t think they are actually connected, this week and last week," he said.

"I don’t think missed tackles ... yeah we missed a lot of tackles last week, but we only conceded two linebreaks and three tries, so it shows there was a lot of blokes working hard, and there was much more resolve.

"This week we probably tackled better but there was less resolve. It’s not consistent to our performance and who we are."