Vaughan was stretchered off after falling in the nets

Vaughan slipped over as he stretched for a wide delivery from net bowler Zac Taylor and yelled out in pain when he rose from the ground.

"As I went to stand up my body twisted and I just felt my knee lock," he said.

Middlesex captain Andrew Strauss has been called up as batting cover, having lost out to Paul Collingwood in the initial 13-man squad.

Vaughan had a scan on his knee later on Monday and the initial prognosis was good.

England and Wales Cricket Board chief medical officer Dr Peter Gregory said afterwards: "The scan showed no significant damage to the knee ligaments.

"However, Michael has a previous history of cartilage problems with the right knee and may have aggravated an old injury.

You can never say never and I will be giving myself every chance to try and get the knee right in time Michael Vaughan

"At this stage, he is in serious doubt for Thursday and will continue to receive treatment from the England medical team over the next 48 hours."

Vaughan had surgery on the same joint in September 2002 to repair torn cartilage.

If he were to miss the opener against New Zealand, it would be the first time he has not played in a Test since becoming England captain last August.

He missed a single one-day international last year after a back spasm.

"It is very frustrating for me, especially after doing so well in the West Indies," Vaughan said.

Marcus Trescothick would be likely to stand in as captain in Vaughan's absence, with Mark Butcher joining him to open the batting.

And it would mean a starting place for Durham all-rounder Collingwood.