Bell ready for call-up as knee injury threatens to put Vaughan out of tour

Vaughan collapsed in a heap at the bowler's end holding the back of his leg after completing a gentle second run during England's three-day game against Pakistan A. He immediately called for assistance and Kirk Russell, the England physiotherapist, raced to the middle. After 10 minutes of treatment, Vaughan limped from the field and had ice placed around the joint. He was subsequently taken for a scan at a local hospital.

The true extent of the injury should become apparent today when the results of the scan become available, and there are fears that the England captain may have torn the cartilage in his knee. There already seems very little prospect of Vaughan being fit for Saturday's first Test against Pakistan, but if he has damaged the cartilage he will require surgery and his tour will be over.

"I was in the process of completing a run when I felt my knee lock on me and I went down straight away," said a dejected Vaughan. "It's sore at the moment but I am going to have treatment on it tonight and we will see how things go over the next 48 hours."

The loss of Vaughan would be a huge blow to England's chances of winning their seventh consecutive Test series. Pakistan are a decent side, especially at home, and Vaughan's leadership has played a massive part in their recent success. Under his guidance England have become a well-directed and disciplined side, and Vaughan is now one victory away from equalling Peter May's record of 20 Test wins.

Vaughan has missed only one of the 32 Test matches since he became captain in 2003, when the same knee collapsed under him during a practice session prior to the Lord's Test against New Zealand in 2004. Marcus Trescothick took charge of the side and led England to a famous victory.

In the probable absence of Vaughan, Ian Bell will get the unexpected opportunity to show that he can perform consistently at the highest level. The indications were that Paul Collingwood would play instead of Bell in Multan, after the Durham all-rounder was chosen ahead of him in England's current game. But Bell now looks set to be given the responsibility of batting at No3 in four days' time.

Vaughan had an operation on his right knee before England's 2002-03 tour of Australia, 20 months prior to the New Zealand game. The injury at Lord's kept him out for just one match but the fact that yesterday's problem came whilst running in a straight line suggests that the 31-year-old will have ongoing issues with the joint.

It may take a couple of days before a proper diagnosis of the injury is made because the results of yesterday's scan need to be compared to those he has had before, which are currently in England.

"Michael has a history of cartilage damage and it is likely that this is what has happened," said Dr Peter Gregory, the chief medical officer at the England and Wales Cricket Board. "The problem he had at Lord's a couple of years ago was very similar but on that occasion he did not need surgery. He responded to treatment quickly and was available for the next Test.

"We are hopeful that the same will happen but his chances of playing on Saturday are slim. If he has a tear his tour will be over. He clearly could not take any further part in the day. It is still very sore and the treatment will be complicated."