Saracens full-back Alex Goode has suffered a shoulder tear and will miss Saturday's trip to face Racing Metro.
A potentially crucial Heineken Cup Pool 1 clash sees Mark McCall's Londoners travel to Nantes but they must make do without England star Goode, who has scored 35 points in his 22 appearances in Europe's elite club competition.
"Alex has a tear in his shoulder," said Saracens Director of Rugby Mark McCall.
"At the minute we are looking at a non-surgical route and there's a chance he could be fit in two or three weeks' time but it all depends how his rehab goes over the next couple of weeks."
The injury also throws Goode's participation in England's Six Nations opener with Scotland on February 2 into doubt.
With Goode absent in France, kicking duties will fall solely on fly-half Owen Farrell, whose defensive contribution in the 32-12 victory over Sale was highlighted by McCall.
"Obviously Owen's goal kicking was good," said McCall. "But defensively he was magnificent because Sale came down his channel with some pretty heavy weapons."