Ireland fly-half Jonny Sexton faces at least ten days on the sidelines according to his Racing Métro head coach, Laurent Labit.
Sexton picked up the knock during the Irishmen's narrow 13-10 defeat to England during Saturday's Six Nations clash at Twickenham.
And while Ireland boss Joe Schmidt initially expected his pivot to be available for the Round Four match-up with Italy, but his participation in the tournament may be over.
"Sexton has damaged ligaments in the thumb and will be unavailable for between 10 days and six weeks," Labit told press in Paris.
Losing Sexton would leave Ulster number ten Paddy Jackson in pole position to fill the vacant number ten shirt, as he did during last year's Six Nations, with Leinster's Ian Madigan and Munster's Ian Keatley both in the frame to come in to the matchday squad.
Sexton is currently the second-highest points scorer in this year's Championship with 32, one behind Wales full-back and fellow British and Irish Lions star Leigh Halfpenny.