Disappointed Penrith coach Ivan Cleary has lamented the Panthers' poor defence as the key factor in their 20-point loss to the Roosters on Saturday.

With the Tricolours simply blowing the Panthers off the paddock from the get-go, Cleary was more than entitled to be critical of his side's poor defence and ill-discipline considering they made 12 errors and missed 42 tackles.

 

Penrith's spine missed 20 tackles between them, and Cleary said his side couldn't stem the flow of the Roosters' easy metres through the middle. 

"It was pretty much one way traffic I thought. We couldn't contain them. We couldn't contain their go-forward and I was disappointed with our defence too. It just wasn't up to it," Cleary said after the loss.

"They were able to get on the front foot early, but defensively we had trouble holding them all game I thought. We looked the best on our goal-line but it was just a bit too easy to get down there. 

"We probably didn't turn up with the right attitude defensively and once they got a sniff they were very hard to stop – they're a very powerful team."

Considering it was just eight days ago when the Panthers produced a shock victory over reigning premiers South Sydney, Cleary remained optimistic for next week's clash with Melbourne if Penrith can improve their defence.

"We're not the only team who are going to lose to the Roosters. We have been going really well the past few weeks but this game showed defensively we are going to have to be much better than what we were," Cleary said.

"That's next week, down in Melbourne it's always a tough game. It's not rocket science what we have to do, we just have to go out there and do it."

In further mixed news, David Simmons may be looking at some time on the sidelines after coming off with a hamstring complaint early on against the Roosters. However, Cleary said Nigel Plum was ok after suffering a concussion and that regular rake James Segeyaro was close to returning from a knee injury.

"Simmons will have to get scans – he had a bit of a hamstring issue and he was a stage where he basically felt it was going to go. I guess the good news is he didn't play on and make it worse," Cleary said.

"[Segeyaro] is close but not exactly sure if it'll be next week or the one after. That hasn't been an issue for us though. We had 17 fit guys out there who were beaten by a better team."