On the same day NSW coach Brad Fittler lost superstar Tom Trbojevic for the season, he would at least have taken some joy in Luai's Saturday night show.

The Panthers five-eighth scored two tries, forced two dropouts, busted four tackles, had three offloads and broke the line once in his second-last hitout before Origin I on June 8.

Teammate Stephen Crichton boosted his case for one of NSW's two vacant centre spots, scoring a length-of-the-field try to put the game to bed in the second half.

It came as defending premiers Penrith underlined their premiership favouritism, backing up their 32-6 flogging of an understrength Melbourne last week with a domination of the Roosters.

The win put them four points clear at the top of the ladder, a handy buffer they will welcome given the amount of players they will have in Origin.

The Roosters could lose a player more immediately, with prop Jared Waerea-Hargreaves on report for a high tackle and sin-binned for dissent.

The Roosters veteran clocked James Fisher-Harris high as he crossed late, and then twice swore when speaking to referee Gerard Sutton when informed it would be a possible eight-point try.

The incident highlighted a sorry night for Trent Robinson's men, who desperately missed the injured Victor Radley's direct running in attack as they often went sideways in their limited time with good ball.

That issue was exemplified by the form of Isaah Yeo in the Penrith line up, who has quickly become the competition's best No.13.

Yeo was influential in Penrith's first try, taking the ball to the line and putting Scott Sorensen through a gap before Luai loomed up in support play.

Luai's second came four minutes later when the Panthers ran it on the last, with he and Cleary combining before the five-eighth spotted a gap when Luke Keary slipped over in defence.

The five-eighth also played a lesser role in the Panthers' next try, forcing a line dropout to give his team one last set before halftime.

They took full advantage, with Apisai Koroisau going over from dummy-half when the Roosters line rushed out expecting a Cleary field goal attempt.

The Roosters in comparison couldn't take their chances when it mattered most.

The hosts had the bulk of the ball in the 20 minutes after halftime but emerged from it even further behind when Crichton marked a Keary kick and went 95 metres to score.

And while James Tedesco and Paul Momirovksi crossed for tries late in the second half, they too often lacked any real punch in attack, posing too few questions for the Panthers.

The only concern for Penrith was Viliame Kikau being placed on report for a late shot on Keary after he kicked.

Australian Associated Press