Gareth Thomas could miss Wales' tilt at a first Grand Slam in 27 years after suffering a suspected broken thumb in Saturday's dramatic 24-18 victory over France in Paris.
Thomas, the Wales captain, has undergone scans in a Paris hospital and faces up to six weeks on the sidelines.
Wales coach Mike Ruddock said: ''We have sent him to hospital. We believe he could have a fractured thumb which could put him out for up to six weeks.
''Obviously that is a blow if it is confirmed.''
Thomas was replaced at half-time by Rhys Williams and missed Wales' remarkable fightback as they turned around a 15-6 deficit to secure their third successive victory of the RBS 6 Nations.
Wales travel to Edinburgh in a fortnight and then host Ireland in Cardiff in the final round of matches.