Newcastle fear former Queensland State of Origin forward Aidan Guerra may have suffered a broken leg as part of a cruel fallout from his side's loss to Manly.
Guerra had to be taken from the field in a medicab late in the Knights' 26-18 loss to Manly at McDonald Jones Stadium on Saturday night, which was also Newcastle's fourth straight loss.
The second-rower was hurt trying to make a tackle on Manly winger Reuben Garrick, and was taken to hospital for X-rays late on Saturday night.
"That's a bad one. From what we believe, he may have broken his leg," coach Nathan Brown said.
"That's a double-whammy - a really poor performance then a broken leg for one of your players, so it's not good."
The loss left the Knights towards the bottom end of the ladder despite entering the season with great hopes of their rebuild coming to fruition.
The Sea Eagles had appeared in control of Saturday evening's match when they led 26-12 with 13 minutes to play, before Mitchell Barnett ran onto a Danny Levi pass to score.
Manly prop Addin Fonua-Blake was sin-binned from the ensuing kickoff, collecting a falling Mitchell Pearce in the head while chasing a ball that hung high in the air.
Pearce failed his HIA and didn't return, prompting Fonua-Blake to be sent on his way by referee Peter Gough.
However, the Sea Eagles held on resolutely, as the Knights failed to crack the 12-man defensive line.
After beating Cronulla in the opening round, the Knights have lost to Penrith, Canberra, St George Illawarra and the Sea Eagles.
They were particularly slow out of the blocks on Saturday, as Manly raced to an 18-0 lead before Ponga kicked them into gear with a short grubber for Edrick Lee, who powered himself over the line just before halftime.
Ponga at least looked dangerous at the back, breaking the line three times in one of the few positives for Newcastle.
Manly have won three games straight, entrenching themselves well within the top eight.
Fonua-Blake was their best before the late sin-binning, providing plenty of early muscle alongside Martin Taupau and scoring a crucial second-half try as he ran through a gaping hole in the Knights' line.
Apisai Koroisau was also better out of dummy-half, breaking through in the lead- up to one try, while Kane Elgey set up one four-pointer with a lofted ball to Jorge Taufua and Jake Trbojevic kicked short for Joel Thompson for another.
Daly Cherry-Evans was also strong as he celebrated his 200th NRL game, running 143 metres, kicking a 40-20 and busting through three tackles.