The Manly coach is still searching for his first victory after the Sea Eagles, featuring Gerringong's Reuben Garrick, slumped to a 26-18 defeat against the premiers, including Kiama product Brett Morris, in a Brookvale slush.

Keary once again proved he didn't mind being a solo act as halfback Cooper Cronk watched from the sidelines with a hamstring injury.

Just as he did in last year's NRL grand final, Keary looked more than comfortable being the red, white and blue chief orchestrator, and laid on all four first-half tries as the Roosters raced out to a 22-nil lead.

"I thought our execution of the stuff we wanted to get on was very high, and I thought the execution of our try-scoring plays, the kicking and end-of-sets were really good,'' coach Trent Robinson said.

"Defensively we were rock solid. But we were a bit stop-start and searching for more once we got ahead, and that kept it to 16-0 for quite a long time.''

Robinson was forced to give his team a proper Bondi major makeover after he lost Cronk and co-captain Jake Friend to a shoulder injury late in the week.

Latrell Mitchell started at five-eighth - a position he had trained in all pre-season as precaution - Mitch Aubusson moved to the centres and Victor Radley started at dummy-half.

Lam, the son of club favourite Adrian, started on the bench before debuting in the second half.

His father tuned in from England and while he originally planned to miss the final 20 minutes because of Wigan's captain's run, he made an exception and even got on FaceTime with his boy.

Lam needed just 10 minutes to deny Jack Gosiewski a try, then laid one on for Boyd Cordner with a lovely kick off the left boot.

The only disappointment for the Roosters was a suspected ''low-strain MCL'' injury to Brett Morris right on half-time.

Morris, who struggled with a knee injury in 2015 and 2016, did not return after the break.

It will not be lost on Robinson he now has three premiership-winning internationals parked in the casualty ward. He will be hoping Cronk and Friend are some chance to play against Parramatta on Friday night.

Manly must go in search of their first win in Christchurch next Saturday in what will be an emotional afternoon against the New Zealand Warriors.

When Manly pair Manase Fainu and Jake Trbojevic bagged two tries in as many minutes approaching the hour mark, the 9664 drenched Sea Eagles fans had some sort of hope.

But the Roosters lead was simply too great, especially in sloppy conditions.

Hasler, like Robinson, will hope his own big-gun Tom Trbojevic will be back from a hamstring injury next weekend.

Clive Churchill Medallist Keary had the ball on a string at the start of the match and his first cross-field kick sailed past Brad Parker then skidded under Jorge Taufua for Morris to dive on and score.

Mitchell then intercepted a Daly Cherry-Evans cutout pass and launched a giant 40/20 that same set. Keary went left again and threw a looping pass for Tupou to take the ball high and plant it in the corner.

Shocking rain fell midway through the half as hundreds of punters on the hill scattered to either end of the ground to seek cover.

They must have been tempted to keep going through the exit doors when Keary took the ball to the line and drew Cherry-Evans and 200-gamer Joel Thompson before squeezing the ball for Cordner to bag his first.

The fourth try was the best as Keary somehow weighted the ball to perfection, just inches above a leaping Moses Suli and straight on to the chest of Tupou. Even Tupou looked briefly flabbergasted by Keary's pinpoint accuracy.

While Keary danced around the park, Jared Waerea-Hargreaves was brilliant up the middle, chalking up 22 hit-ups for more than 250m.

Manly never looked like scoring and just as they did in the wet last Saturday, the home side struggled to complete their sets.

Hasler took to the home coach's box for the first time since 2011 but was not about to reminisce.

"I don't get caught in that much, it was a big game, it was two points at stake, and you're playing against a very classy outfit in the Roosters,'' Hasler said.

"We know if we can address those areas of possession and building pressure and aspects of our kicking game, we're a competitive outfit, and it will happen. I'd like it to happen a little quicker, but we'll keep working.''