Wales and Charlton Athletic midfielder Jonny Williams has suffered a setback in his comeback from injury following a mishap in training.
The 26-year-old has now been ruled out for a further two weeks.
Williams had been pencilled in for a return to action this weekend having missed two months with a knee injury.
But an "air shot" in training caused him to tear his hamstring, with Addicks manager Lee Bowyer confirming more time on the sidelines.
"Jonny Williams was meant to be back. He had an air-shot and missed the ball and his hamstring went tight," said Bowyer.
"He's had it scanned and he's got a grade one hamstring tear. So, he's out for two weeks."
Williams has not played since a 3-0 loss to Derby on 26 October, before suffering the knee problem that required surgery.
Having broken back into Ryan Giggs' Wales side, the injury forced the 21-cap international to miss the climax of the successful Euro 2020 campaign, where wins over Azerbaijan and Hungary booked a place in next summer's finals.
Williams could now be back for Charlton's all-Championship FA Cup third round tie with West Bromwich Albion on 5 January.