Midfielder Aaron Ramsey is a doubt for Wales' World Cup qualifiers against Macedonia and Serbia in September.
Ramsey scored twice as Arsenal confirmed their place in the Champions League group stages with a 5-0 aggregate
win over Fenerbahce.
But the Welshman finished the match on the bench with a groin problem after Arsenal had used all three substitutes
"I don't know how bad Ramsey is," Arsenal manager Arsene Wenger said.
"I took him off with three or four minutes to go, but I don't know how bad it is. He wanted to stay on."
Ramsey is a doubt for Sunday's derby with Tottenham and the Gunners will be without Lukas Podolski, who faces three weeks out after suffering a hamstring injury against Fenerbahce.
The 22-year-old has been included in the Welsh squad but the absence of the in-form Ramsey would be a blow ahead of the forthcoming double header.
Wales travel to Macedonia for a qualifier on Friday, 6 September before hosting Serbia at Cardiff City Stadium the following Tuesday.
Chris Coleman's side are realistically unlikely to qualify from Group A as they are lying 13 points behind leaders Belgium and 10 adrift of second-placed Croatia.