Warburton has had a scan on the shoulder with the injury similar to one he suffered during the 2012 Six Nations decider against France, which kept him out for nearly three months.
It is the latest injury blow to Warburton in recent months, with the 25-year-old having missed the deciding Test for the British & Irish Lions against Australia with a hamstring injury this summer.
"Sam has had a scan and it's just a case of waiting for results," Cardiff Blues director of rugby Phil Davies said. "We don't know yet. It's a similar injury to what he has had previously, but we don't know how bad it is."
Warburton is one of 12 Cardiff Blues players ruled out for the game, with fellow Lions star Gethin Jenkins also among the walking wounded.
Leigh Halfpenny has shaken off a knock he picked up in the Australia defeat, however, and is expected to play.