Manly are under pressure to recall banished half Jackson Hastings after Lachlan Croker suffered a potentially season-ending knee injury in Friday's 18-12 NRL loss to Newcastle.
The Sea Eagles' injury crisis worsened with five-eighth Croker taken from the field with a suspected ACL injury in the 30th minute at Lottoland.
Hastings was last week told he would play reserve grade for the rest of the season after an altercation with Daly Cherry-Evans in Gladstone.
However coach Trent Barrett may have no other option than to turn to the former Sydney Roosters playmaker against South Sydney next week.
It was a deflating fourth loss in a row for the Sea Eagles while for the Knights it was a big boost for their confidence without star playmaker Mitchell Pearce.
Emerging superstar fullback Kalyn Ponga was the hero, putting Nathan Ross over for the match-winner in the 76th minute.
At 10-10 the Knights appeared to be setting up for a field goal but Ponga decided to run it down the left side before putting Ross through a hole.
Croker has previously suffered two ACL tears and a third would be a devastating blow for his career having this year finally established himself as a regular first-grader.
Manly are now deep in the grip of injury with Croker's problem meaning Barrett has just 22 fit men at his disposal.
Darcy Lussick (released), Curtis Sironen (knee), Jorge Taufua (collarbone), Brad Parker (knee) and Kelepi Tanginoa (knee) are all unavailable, leaving them on the verge of desperation.
The home side were reduced to a two-man bench when winger Matthew Wright suffered a concussion and did not return after halftime.
Despite this, the Sea Eagles went ahead 10-4 when Shaun Lane charged over off a Cherry-Evans short ball.
But just when it looked like Manly were winning the arm-wrestle, they went to sleep and Knights hooker Slade Griffin forced his way over to even the scores with 20 minutes remaining.
Ponga showed poise beyond his years to guide the Knights home.
Martin Taupau was immense for the Sea Eagles, charging for 225 metres from 22 carries while Jake Trobojevic was similarly tireless, making 200 metres before being sin-binned in the dying moments.