Terry Campese had to be helped from the field during Hull KR’s defeat to Huddersfield on Sunday.
The 31 year-old, who has been out of action since rupturing his anterior cruciate ligament last June, suffered a hamstring injury 58 minutes into the loss at the John Smith’s Stadium.
New Robins interim head coach James Webster told Sky Sports: “When he’s on the ground with his hand up in the air, you think ‘has he done his knee?’ but it’s the hamstring in his other leg.”
“While we’re obviously disappointed, it’s good that it’s not his knee. We’ve no idea how bad it is but he’ll definitely miss some period of time.”
“He’s an experienced player who understands injuries happen in the game. I’m sure he’ll be doing everything possible to get back as quickly as he can.”
The stand-off set up Rovers’ only try of the game as the visitors crashed to a 38-6 defeat, leaving them at the foot of the table with just a solitary point from their opening six matches.