Wales midfielder Aaron Ramsey is an injury doubt for October's World Cup qualifiers against Austria and Georgia.
Ramsey, 25, has not played since injuring his hamstring in Arsenal's loss to Liverpool on the opening day of the season.
Wales play Austria away in Vienna on Thursday, 6 October before hosting Georgia in Cardiff three days later.
"There is concern because he has been out for so long," Wales assistant boss Osian Roberts told BBC Wales Sport.
"It's extremely disappointing after the magnificent tournament Aaron had at the Euros that he picked up an injury in the opening game of the season.
"It's a huge disappointment for him and for all of us. But let's just hope the situation improves for him over the next week or so."
Ramsey missed Wales' 4-0 win over Moldova in their opening 2018 World Cup qualifier in September.
Arsenal manager Arsene Wenger said the former Cardiff City midfielder would be "back after the [September] international break" but it now appears he could miss the second and third fixtures of Wales' current campaign.
Ramsey was regarded as the outstanding performer in Chris Coleman's squad during Wales' unprecedented success at Euro 2016.
He was named in Uefa's official team of the tournament after helping Wales reach their first semi-final.
But Ramsey missed the 2-0 semi-final loss to Portugal after picking up two yellow cards during the opening five games.