Penrith Panthers coach Anthony Griffin has confirmed star playmaker Nathan Cleary will return from injury next week against the Wests Tigers.

"He [Cleary] finished off his rehab today and had a tough session this morning down at Penrith and he'll re-join the team tomorrow," Griffin said.

"It's good to get Nathan back and Tyrone [Phillips] may play his first game in the NSW Cup on Sunday and [Jack] Hetherington will be back after suspension.

"So it will be a nice change having three or four back rather than what we have been going through over the past three or four weeks."

Griffin put Friday night's 29-18 win over the Newcastle Knights down to his side's defensive performance.

Leading 18-6 at halftime, the visitors had to absorb nearly seven minutes of defending on their own line, in which they only conceded one try, before regaining momentum.

"It went a long way to us winning the game, the defensive effort early in the second half," Griffin said.

"I think at one stage they had 10-12 sets to our one or two, and our start obviously put us in a good position, but that period just held them off long enough."

Peter Wallace commended his side's effort given the cold and windy conditions.

"It [the defensive period] allowed us to take stock, and we got a bit of possession late in the half and set us up for a good win," the hooker said.

He gave a special mention to prop Trent Merrin who played just days after surgery on a fractured finger. Merrin's night included 16 hit-ups and 24 tackles in 54 minutes of work.

"It was a big effort for Mez to play this week," Wallace said.

"Everyone saw his finger last week, and he only got operated on, on Sunday, so to play 4-5 days later is a really big effort."