Parramatta's nuggety lock Nathan Brown looks set for an unwanted spell on the sidelines after he damaged his left pectoral muscle in Sunday's 20-12 win over the Penrith Panthers.
Brown was inconsolable in the dressing sheds after he was assisted from the field by two trainers in the 17th minute, cradling his left arm in his jersey, which acted like a sling.
The pectoral connects the arm to the chest muscles and Brown may need surgery based on the severity of the tear.
The 26-year-old forward, who is one of the most aggressive and talented of the Eels pack, had made a regulation tackle on his opposite No.13 James Fisher-Harris. He then got up and reached out to grab Panthers centre Dean Whare but withdrew his left arm in sharp pain.
He lay on the ground in obvious distress while Eels staff worked on him.
"He's not good. I think it's his pec and that's three months," coach Brad Arthur said.
"It's tough but we lost a couple at the start of the week when we thought they might play. But Kane Evans and David Gower came in and got an opportunity and didn't let us down."
Rooster skipper Boyd Cordner suffered a pectoral tear last season and spent 10 weeks on the sidelines.
Despite the blow to Brown and the Eels forwards, Arthur was full of praise for young five-eighth Dylan Brown on debut and his partnership with halfback Mitchell Moses.
"[Brown] showed good calmness and composure which is what we talked about during the week with him and all pre-season as that's what we liked about him," Arthur said.
"He's trained like that all pre-season and a good indicator that he was ready was the excitement in his teammates to have him on the field.
"And that composure was really good for Mitch. He stuck to our plan and got the job done for us today Mitchell.
"He's gone away and worked really hard … [in off-season] ... had a lot of self-reflection and has come back with a real resolve. He knows what he needs to do and he's done that himself," Arthur said, on hoping the Moses of old would be here to stay.
"I was happy with our resolve to hang in there.
"There's still a tonne of stuff we've got to do better especially with some of our attack.
"But if we are disciplined and give ourselves time, we'll get better in time.
"That's how we played in '16 and '17 but we didn't look like that last year.
"Regardless of the result today I was happy that we looked like that team again."
As for Michael Jennings's 54th-minute sin-binning over contact with Isaah Yeo's head that forced the Penrith back-rower from the field and might attract match review committee attention, Arthur labelled it "accidental".
"He was going in aggressive to compete in a tackle and the bloke has fallen. That's a hard one for him," Arthur said.
"But he came out and his next action to make up for the 10 minutes was that chase to push someone into touch off a kick so it was a good response."
Jennings also scored his second, and the last of his side's four tries, in the 76th minute.