Sezer had already been ruled out of Friday night's away game against Cronulla, with scans revealing a lower grade hamstring injury.

He is now certain to miss next week's match at AAMI Park against reigning premiers Melbourne, but is still a chance to return for the round 21 clash with Penrith.

Sezer's absence comes at the worst possible time for the Raiders, who are making a late charge at the finals without five key players.

Captain Jarrod Croker is out for the rest of the season to have surgery on his dislocated knee cap, while Shannon Boyd (calf), Joseph Tapine and Jack Wighton (both suspended) are also missing.

Despite their availability woes, stand-in skipper Josh Hodgson says the Raiders believe they can cause an upset against the Sharks.

"He's (Sezer) a big part of our team and with a few people out already, it certainly doesn't help to have Aidan out as well," Hodgson said.

"We'll do everything we can to get the result and do everything we can to make sure we get the two points because we're chasing the eight now and need to pick up all we can."

Australian Associated Press