Referee Peter Gough labelled the tackle ”serious foul play”, which drew an immediate surprised response from skipper Daly Cherry-Evans.
Fonua-Blake had only a few minutes earlier scored the easiest of tries through a yawning gap to all but seal the result.
The young Tongan prop was suspended in the opening round for taking out Benji Marshall after he had kicked, but has been nothing short of brilliant for the northern beaches club.
If he is rubbed out he will be sorely missed by the Sea Eagles as they chase a fourth straight win against St George Illawarra next Saturday night.
Klemmer stormed off after the game and did cross paths with Fonua-Blake.
Manly’s eight-point win meant Des Hasler had done what Trent Barrett was unable to do last year – win three on the trot.
Cherry-Evans celebrated his 200th game in style, and the skipper thought he had helped himself to a first-half try when he skipped around Kalyn Ponga, only to have the ball knocked out from behind by Edrick Lee.
For the Knights, it was their fourth straight loss as talk about the future of Nathan Brown will become a hot topic.
To make matters worse, the Knights lost Aidan Guerra to a suspected broken ankle late in the game.
Guerra burrowed his way over from dummy half in the second half to score a try, even though it appeared he had planted the ball down short.
Ponga was forced from the field for a head-injury assessment in the first half when hit by Curtis Sironen. But unlike Pearce, Ponga was able to pass his HIA and return.
Manly burst out of the blocks to lead 18-0 after 20 minutes with tries to Jorge Taufua, Reuben Garrick and Joel Thompson. Jake Trbojevic picked up the try assist for Thompson when he dropped the ball on to his right boot.
Few gave Manly a chance up the other end of the M1 Motorway because of the hamstring injury picked up by their most dangerous player, Tom Trbojevic.
The Knights coughed up too much ball and because of that were never going to take advantage of the 7-2 first-half penalty count.
Ponga was the provider for their only points in the first half when he kicked for Edrick Lee to storm through and do well to shake off Garrick to score.
The Knights must now regroup ahead of their road trip to the Gold Coast next Sunday.
Christian covers rugby league for The Sydney Morning Herald.