Wales are reviewing the fitness of scrumhalf Rhys Webb ahead of this weekend's Six Nations finale at home to Scotland, assistant coach Stephen Jones said on Tuesday.
Webb suffered a knee injury during Wales' 38-21 warm-up defeat by France in Paris last Saturday.
Cardiff Blues scrum-half Lloyd Williams, who won the last of his 28 caps four years ago, has been called into the Wales squad as cover ahead of Saturday's match against in Llanelli.
If Webb is sidelined, Scarlets scrum-half Gareth Davies would be in line for a Test start on his region's home ground, with the west Wales outfit's uncapped Kieran Hardy also in the squad.
"Hopefully, it's not too serious, is the answer to Rhys. We are assessing him on a daily basis," former Test fly-half Jones told reporters.
"We know Lloyd is an experienced scrum-half with a very good balanced game. He's a very smart rugby player, so we know he can pick up our game-plan very quickly.
"He (Webb) has had his bump to the knee, and we will be guided by the medical guys on this. It's a waiting game, but we will find out from them," Jones added.
Wales coach Wayne Pivac and Scotland counterpart Gregor Townsend are due to name their teams on Thursday.
Pivac's side are on a run of four successive defeats, with Scotland aiming for their first away win in the fixture since 2002.
The match should have been played in March but was put on hold by the coronavirus outbreak that delayed the finish of this year's Six Nations.
Scotland are currently fourth in the standings to Wales' fifth ahead of a match moved from Cardiff to Llanelli after the Principality Stadium was commissioned as a field hospital by the Welsh government in response to the pandemic.