Manly prop Addin Fonua-Blake.

Des Hasler has hailed Manly's seismic upset of the Sharks as one of the best wins in the club's 72-year history.

Led by a similarly top-shelf performance from Tongan powerhouse Addin Fonua-Blake, the Sea Eagles shocked Cronulla with a 28-16 boilover that came with over $2 million of their salary cap watching from the sidelines.

Manly march on to take on South Sydney next Friday night with star prop Martin Taupau to return from suspension. On the downside, the likes of Tom Trbojevic, Joel Thompson, Curtis Sironen and Taniela Paseka will all still be sidelined through injury.

With a full casualty ward, several rookies replacing their biggest names, Lottoland's asbestos concerns and Paul Gallen's retirement motivating Cronulla, Manly were given Buckley's of progressing past week one of the finals, only to emerge with a famous win in front of an ecstatic maroon and white faithful.

"I said yesterday it had that script about it," Hasler said of a Manly backs-to-the-wall classic.

"It's great for this side and a young side to experience something like this tonight.

"It's a great confidence thing for them. For some of them it's their first semi-final.

"It doesn't come much harder than that baptism of fire against a pretty experienced Sharks side.

"It's a great win, a very proud win in this club's history."

Fonua-Blake claimed man-of-the-match honours and an emphatic victory in his running battle with Gallen, finishing with a game-high 187 running metres and leading the Sea Eagles' forwards in Taupau's absence.

His 51st minute try also helped seal the win too as Cronulla fought back from an 18-0 deficit to reduce Manly's lead to eight points after halftime.

"Addin, it was probably one of his best games," Hasler said.

"He laid a real platform for us and the boys got on the back of it. He certainly created great momentum for us, he led the way there. And the other boys got on the back of it.

"We need to maintain that, it will go up a notch next week against South Sydney. That will be a good game come Friday."