Reading manager Steve Coppell fears that four of his injured stars will not be fit enough to feature in this month's Peace Cup in South Korea.
The Royals face River Plate in Suwon in their opening group game in ten days' time, but Marcus Hahnemann, Glen Little, Ibrahima Sonko and Bobby Convey are still struggling with injuries they sustained last season.
Coppell told the club's official website: "Marcus has got his hand injury, and we've got to make some decisions.
"Glen Little didn't start with us (at pre-season training) on Thursday, and there's Bobby Convey as well. We need to decide if they can play a part.
"I'm not sure of the benefit of travelling just to train, there's maybe more point staying here.
"Sonko's still looking at September, which has been the target since day one. That would be six months.
"He's jogging around again now, not freely, but it's still great progress."
After playing River Plate, Reading are scheduled to play Lyon on July 16 and Shimizu S-Pulse three days later.