The Sea Eagles will go into Sunday's crunch clash with the Knights without halfback Daly Cherry-Evans, who is away preparing with Queensland.
In Manly's only other game without their star No.7, a severely undermanned side struggled to land a blow in attack in a 14-0 loss to South Sydney.
The Sea Eagles have the worst record in the NRL during the Origin period in recent years, winning just won of nine games without their representative players since 2016.
They will at least possess more strike weapons this week, with Tom Trbojevic back from injury and Haumole Olakau'atu also available after being dropped by NSW.
Souths players enjoy Keaon Koloamatangi's try in the win over Manly. (James Gourley/AAP PHOTOS)
Five-eighth Luke Brooks says the team have also learned from the gritty affair against the Rabbitohs.
"It was just a bit about detail we need to fix up," Brooks said.
"We had a few players out and our attack wasn't where it has been all year. Learn a fair bit off that and we'll get that going into this week.
"I've (taken on the controlling role) pretty much my whole career, so it's nothing new to me.
"Obviously we lose a lot with Chez going out. But I've done it my whole career."
One option could be to hand Humphreys a debut alongside Brooks in the halves.
Winger Tommy Talau filled in as a five-eighth three weeks ago against Souths, but Humphreys was spotted training with Brooks on Tuesday.
The son of former Sea Eagles CEO Stephen Humphreys, Jamie has already signed a deal with the Rabbitohs for next year.
"He's a great player," Brooks said.
"The way he trains, he trains so hard. You know what he's going to bring to you. We have plenty of trust in him if he does play.
"It's hard. Tommy (Talau) has played centre and wing his whole NRL career.
"To step up and play in the halves, it's a tough job. If we do go with a genuine half, it will help."
Meanwhile Manly have lost fullback Tolu Koula for six weeks to a medial ligament injury, needing surgery on his knee.
Tolu Koula charges the ball back against the Cowboys in Townsville. (Scott Radford-Chisholm/AAP PHOTOS)
Sea Eagles players revealed on Tuesday that Koula was injured in his first tackle of Saturday night's golden-point win over North Queensland, before he played on and ran 309 metres with ball in hand.
"You wouldn't know he got injured in his first tackle," Brooks said.
"It just shows how tough he is. He did something similar when he went to fullback in the Broncos game, he did his shoulder and played on with it."
Manly could end Trbojevic's centre experiment early and move him back to No.1 in place of Koula, or pick Lehi Hopoate at the back.
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