Ireland prop Cian Healy is a major doubt for the Six Nations opener with Wales on February 7 after undergoing knee surgery.
Healy is serving a two-week ban for striking Guilhem Guirado during Leinster's European Rugby Champions Cup clash with Toulon on December 13.
The 28-year-old was ineligible for selection until Monday January 11, but is now expected to spend even longer on the sidelines after the procedure on his right knee.
That puts his participation in the first game of Ireland's Six Nations defence under threat. which will be another blow to coach Joe Schmidt after Tommy Bowe ruled himself out.
"Cian Healy underwent a scope and clear-out of his right knee yesterday afternoon," Leinster confirmed in a statement.
"This was an elective procedure and while we are still waiting for the report, it is expected that he will be out for three to four weeks."