They opened with a month of blockbusters, but Sydney Roosters coach Brad Fittler says Saturday's `mockbuster' at Penrith is his side's toughest challenge thus far.

On paper the Roosters are expected to thump the Panthers at CUA Stadium, they have won their past four visits to the foot of the mountains and are the NRL benchmark after starting with a three impressive wins and a close loss.

But the loss of fullback Anthony Minichiello (back), prop David Shillington (alcohol breach) and backrower Willie Mason (knee) will test the Roosters depth and the lack of hype surrounding the clash will challenge their ability to play with the right intensity.

The Roosters' four opening games - South Sydney, Brisbane, Melbourne and Bulldogs - all had finals intensity due to the fierce rivalries and high profile opponents that generated increased media exposure.

But Saturday's visit to Penrith is much more low-key and Fittler is wary that the quiet build up may translate to their on field intensity.

"It's a big test, whether it's depth or attitude or being able to bounce back or whatever it is this is a very very important game for us," said Fittler.

"Penrith on a Saturday night at 7.30pm, I suppose is going to be different to Canterbury with 40,000 and a big build up so this is a real challenge.

"We actually spoke about (complacency) last week. You're going to have games that are pumped up and then there's going to be games which are going to be tougher to get yourself up.

"That's all about being a footballer all year round and it's going to be a real good learning curve for all of them."

Winger Amos Roberts admits night games in Penrith can be tough to lift for, but says the Roosters are aware of how dangerous the Panthers can be and won't be taking the clash lightly.

"It's kind of hard because they can play good against good teams and kind of drop a lot of ball against the other teams," said Roberts.

"We have to be mentally tough on Saturday night and keep playing the way we have the last four weeks.

"Going to Penrith on a Saturday night, it can be very cold and it might be raining ... it's going to be tough and we just need to be mentally ready for it."

Fittler meanwhile said he may yet decide to play Mason and has given the new recruit until game day to overcome his grade one medial knee ligament tear.

Fittler says Mason's mere presence would ensure the Roosters turn up with the right intensity.

"We need those blokes able to back up and show the others what it takes," he said.

"I want him to play every week."

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