Hughes was injured during a Fulham training session last week

The Fulham defender sustained ligament damage in training last week and he could be out for as long as six weeks.

That could also rule the 27-year-old out of next month's Euro 2008 qualifiers against Latvia and Iceland.

"I couldn't believe it. It happened in the last kick of the ball at a session last Tuesday," Hughes told BBC Sport.

"Thankfully, the injury has responded well to treatment but it's bad timing with the Liechtenstein game coming up.

"Six weeks out is the worst-case scenario and I'm still hopeful of being involved in the games against Lativa and Iceland."

The Latvia game takes place in Riga on 8 September while Nigel Worthington's squad face Iceland in Reykjavik four days later.

Damien Johnson is also a fitness doubt for the game against Liechtenstein.

The Birmingham City midfielder has a hamstring injury and is certain to miss the start of the Premiership campaign.

The injury to Hughes means that George McCartney is in line to earn an immediate recall against Liechtenstein.