Dave Kitson is not expected to return until mid October with the Reading striker's rehabilitation progressing slowly.
Kitson sustained a knee injury on the opening day of the season following a challenge from Middlesbrough's Chris Riggott and has been sidelined since.
The 26-year-old should complete his recovery after the international break with the Premiership clash against Chelsea on October 14 a possible comeback game.
Reading boss Steve Coppell told the club's official website: 'It's going slowly and that's a concern. We had expected more progress.
'The doctor who has been treating him has been away. He's had three injections and has one more to come.
'I think that will be the last and we hope for a response from it. We're not looking at surgery, time will heal it.
'Realistically we're looking after the international break.'