Keith Earls was "walking around okay" after the game said Ireland coach Joe Schmidt as he provided a cautionary update on the winger's fitness.
The 31-year-old Munster man, who was making his first appearance of the season after a knee tendonitis complaint, limped off the field 13 minutes into the second half of the 19-10 win over Wales.
"It just seemed like his quad, whether it's a whack in the quad or just above the knee, he was uncomfortable," Schmidt told reporters afterwards.
"Those sort things you've just got to wait and see if it's okay tomorrow.
"Potentially, he could have played on but, he feels like he could have but there's no way in a game like that you are going to keep someone on in those circumstances.
"It was good to get him off and once he cools down completely and we maybe get a good look at him tomorrow, we'll have a bit more information."
Prop Cian Healy failed a Head Injury Assessment at half-time and was replaced by Dave Kilcoyne but Schmidt was confident it would not threaten the Leinster man's place in the squad, which departs for Japan on Wednesday.