The Round 16 contest between Manly and the Roosters was as physical as any this year, with three players leaving the field concussed.
Roger Tuivasa-Sheck opened the scoring, then the Roosters created an overlap just five minutes in before Manly returned fire but were unable to capitalise on several attacking opportunities.
A 20-metre dash from dummy-half from Jake Friend embarrassed the Manly marker defence to make it 8-0 after 25 minutes, the absence of regular goalkicker James Maloney helping to keep Manly in the game.
There were no further points in the first half, and the Roosters were also guilty of failing to take some chances, notably when a 50-metre line-break from Sonny Bill Williams resulted in a fumbled pass to an unmarked Jennings.
Manly finally got on the board shortly after halftime when good lead-up work from Glenn and Brett Stewart helped put Jamie Lyon over, before a long-range movement from the Roosters resulted in Michael Jennings stretching the lead back out to 12-6.
A contentious penalty allowed the Roosters to make it an eight-point lead with 20 to play, then a sublime drifting run and offload from Williams to Jennings made it 18-6.
A late try to Manly prop George Rose in a desperate attempt at a fightback wasn’t enough as the Roosters held on 18-12.