Ireland fly-half Jonathan Sexton faces a race against time to be fit for the autumn internationals after breaking his jaw while playing for Racing Metro.
The 29-year-old British and Irish Lions star was injured in a heavy clash with Craig Burden in Sunday's French top-flight contest against Toulon.
South African hooker Burden was sin-binned for the challenge.
The first of Ireland's three autumn games is against South Africa in Dublin on 8 November.
They then host Georgia and Australia, with head coach Joe Schmidt keen to ramp up the long-range preparations for 2015 World Cup.
Schmidt hopes Sexton will complete a move back to Leinster from Parisian side Racing Metro next summer, although the French club are keen to retain his services.
The 45-cap playmaker is arguably Ireland's most important backline general now that Brian O'Driscoll has retired, so Schmidt will give him every opportunity to make the fitness grade for the autumn series.
Sexton - Ireland's only frontline star plying his trade overseas - endured a difficult first campaign in France last term.
He played 13 club games in 12 weeks after joining the Paris side, much to Ireland's frustration, with former Leinster boss Schmidt unable to dictate how often Sexton turned out for his club. Ireland's home-based stars are subject to the IRFU's player management scheme, which limits the number of games they play.
Sexton duly picked up a leg problem, which put his participation in last year's autumn series in doubt. He sat out the first game against Samoa but was in the team for the big clashes with Australia and New Zealand.
Ulster's Paddy Jackson would be the front-runner to start in Sexton's absence after filling the fly-half understudy role last season.
Leinster's Ian Madigan would also come into the frame, while fast-progressing Munster duo Ian Keatley and JJ Hanrahan are coming up on the rails.