Cardiff - Wales suffered a Six Nations injury scare on Friday when Scarlets wing George North was stretchered off during his club's 47-17 defeat against Ulster in the Celtic League.
North was forced off in the second half at Ravenhill after appearing to take a blow to the head in an accidental collision.
The injury gives Grand Slam champions Wales a major worry ahead of their Six Nations campaign, which kicks off against Ireland in Cardiff on February 2.
North, 20, has scored 11 Wales tries in 26 appearances, including two on his 2010 debut against South Africa and it would be a major blow to his country if he missed the Six Nations.
Wales flyhalf Rhys Priestland is already out of the 2013 campaign because of a torn Achilles.
Scarlets backs coach Mark Jones couldn't confirm the extent of the injury at this stage, saying: "I only know what I saw on the replay. He's had a knee to the head and he's struggling with some head and neck issues."
North's premature exit capped a miserable day for Scarlets as Celtic league leaders Ulster ran riot.
Ulster's 12th win in 13 league games included second half tries from Robbie Diack, Andrew Trimble, Nick Williams, Neil McComb and a penalty try.
Ruan Pienaar kicked all four conversions and two penalties on his 50th appearance.