Manly coach Trent Barrett refused to debate the merits of continuing to leave Jackson Hastings on the sidelines as his team is starting to fall down around him.

As if the club's ongoing salary cap woes, and the exiling of Hastings to Intrust Super Premiership games because of team chemistry, weren't enough then in the 18-12 loss to Newcastle on Friday night – their sixth loss in eight rounds – Manly were forced to add more players to their lengthening injury list.

Five-eighth Lachlan Croker will undergo scans to confirm whether he has torn his anterior cruciate ligament for a third time. He will be the third Manly player to suffer a season-ending ACL for this Telstra Premiership season.

Then back-rower Jack Gosiewski came from the field with a suspected broken hand, while winger Matthew Wright could not return from a head knock and will have to pass concussion protocols before next Sunday's match against the Sydney Roosters. Winger Jorge Taufua (collarbone) is still a month away.

Match Highlights: Sea Eagles v Knights - Round 8, 2018

"We think he's done his ACL... that'll be his season. The poor kid is shattered," Barrett said of Croker. "He's had a few already and I thought he was playing his best game for the club tonight.

"We're just not getting any luck at the moment. But in terms of effort, I thought it was extremely courageous from the team. If you wanted to see if the team was together, I think that was a pretty good example of it.

"But if I don't laugh, I'll cry at the moment," Barrett added, referring to his ever-growing casualty ward.

One obvious solution is to bring Hastings back into the NRL squad. He is a quality halfback, who can also play hooker.

"We'll consider it on Monday. I'm not going to sit here and make any comments," Barrett said.

"I certainly want to keep the headlines away from that if I could and focus on the effort those players threw up."

When pushed on Hastings being welcomed back to the squad – or at least being considered – Barrett seemed to shut that option down.

"[Manly CEO] Lyall [Gorman] will be considered [to play] this weekend, so will Mickey Mouse ... if that answers your question," he said.

But Barrett can't joke his way out of the predicament the Sea Eagles in, with just 21 players to choose from. And he must name 21 on Tuesday.

"We can call on our development list – there's a few of them – so it's something we'll consider over the weekend because we've got some decisions to make," he said.

"It's been extremely difficult. But I'm a half-glass-full sort of person and I can take a lot of positives out of how hard they fought for each other – and it's been a difficult week.

"We put ourselves in a position to win the game, against all odds. That's what I'm going to focus on and keep the group together. We can't change what's happened.

"There's a couple of spots available but we're not going to be able to go out and buy a Johnathan Thurston or Michael Morgan. But we'll make a decision we think that works. I haven't got my head around it too much."

Regular hooker Api Koroisau stepped into the No.6 role after Croker went down in the 31st minute, but Barrett doesn't want to keep him there.

"It'd rather not. He's our best hooker and has put himself into contention for NSW [in that role]."

As for Jake Trbojevic, who was sin-binned in the 80th minute for back-chatting, Barrett wasn't perturbed.

"Just frustration mate. He wears his heart on his sleeve. But while we've got blokes like Jake in the joint, we'll be okay."