Wales coach Warren Gatland has confirmed Dan Biggar sustained an ankle strain in the 16-16 Six Nations draw with Ireland on Sunday.
Biggar managed just one failed penalty kick before limping off after 20 minutes with a knock sustained at kick-off as he rushed to collect the ball.
Rhys Priestland performed well in Biggar's place but Gatland will be keen to have his first-choice fly-half available for the home clash with Scotland on Saturday.
"Dan Biggar has an ankle strain, we'll know more in the next 24 hours," Gatland told a news conference.
"Rhys did well. We tried to play a bit more rugby, we expected more kicking. I thought both sides were good in the conditions."
Wales had already been dealt an injury blow when the late withdrawal of full-back Gareth Anscombe prompted Gatland to call on Liam Williams - himself on the road back to fitness.
"Liam did okay," added Gatland. "He's still not as sharp as we would like him. He had a couple of nice touches.
"Gareth had a tight hamstring and pulled out of training. He still felt the tightness and medically we made that decision last night.
"It wasn't worth the risk starting with him without much cover. If he pulled his hamstring it would have been a six-week injury.
"[The decision] was made in conjunction with the medical team and by Gareth. He was disappointed but that's the way it goes."