A week after being flogged 40-12 by Melbourne, the Sea Eagles' defence remains the biggest talking point headed into Friday night's semi-final against the Sydney Roosters.

Manly have not advanced out of the second week of the finals since the 2013 grand final loss to the Roosters, stumbling in the semi-finals twice.

While this year marks their best shot at adding to their nine premierships, they know they must be far better than they were against Melbourne.

Last week's avalanche of points was Manly's worst defensive outing since the opening month, when the Roosters, South Sydney and Penrith all ran riot against them.

But Hasler insisted on Thursday that the defensive frailties exposed by the Storm was a one-off, and not his side falling back into old habits.

"Definitely (different). The two are totally unrelated," Hasler said.

"We treat last week as a one-off."

Hasler dismissed any suggestions his team's poor record against top sides could be a psychological issue.

Manly are yet to beat Melbourne, Penrith or the Roosters this year, and hold a 3-9 record against the remaining finalists since the competition returned with the set restart rule last year.

"That is the last thing (on our mind)," Hasler said.

"I don't think we're worrying about that. That doesn't come to mind at all."

Hasler has, however, reason to believe his defence can be tightened.

Lachlan Croker has been cleared to return at hooker after a minor back complaint kept him out last week, with Hasler praising his defence in the middle.

He is also adamant that they were as much to blame for the failure to get Tom Trbojevic involved last week as anyone else, after the fullback had his quietest game of the year.

"We didn't play at a level of semi-final football in regards to the ball," Hasler said.

"If you're not going to do that and fight and manage your possession, then it's going to be difficult to get anyone into the game. Let alone Tom.

"When it comes down to it they know they can do better.

"They want to perform better. And then we need to. That's their job."

Australian Associated Press