The back injury sustained by Cameron Smith in Melbourne Storm's win against Parramatta Eels on Friday is not "too serious", according to coach Craig Bellamy.

Smith was forced off in the 35th minute of the 20-4 win at AAMI Park and did not return to the action, with Suliasi Vunivalu, Nelson Asofa-Solomona and Brandon Smith later joining him in the locker room to leave Melbourne without a body on the bench.

The latter pair are expected to be long-term absentees due to ankle and knee issues respectively, while Vunivalu is set to be out for up to a fortnight with a hamstring problem.

Bellamy does not think the captain will be ruled out for a prolonged period, though, with the quartet to undergo further examinations over the weekend.

"Cameron has had spasms in the joints in his back, which he has had before," said the Melbourne coach.

"I don't think it is anything too serious but what serious is, I don't know, especially with backs.

"Brandon and Nelson are going to be out for a fair chunk of time I think.

"Suli felt his hamstring, it wasn't too bad, but we weren't prepared to put him out there for the second half. Our physio basically said it will get worse and if he tears it, that is a six-week injury.

"He is going to miss a week or two but it won't be long term like the other two."