England captain Michael Vaughan underwent a scan on Monday to find out if an old knee injury will keep him out of the first Test against Pakistan.
The 31-year-old faced just one ball before retiring hurt in England's second innings against Pakistan 'A'.
A team spokesman said the results of the scan would be known by Tuesday.
"We need 24 to 48 hours to see how he responds to treatment and, of course, see the extent of damage in the scans but he is in pain and limping," England team doctor Paul Gregory said.
Gregory added Vaughan had a history of cartilage damage and it was very likely the same problem could have occurred again. He missed a Test against New Zealand with a knee injury last year.
"Michael collapsed after hurting his knee earlier today and his knee was certainly painful and clearly he couldn't take any further part in the match," Gregory said.
"The knee is still very sore we are waiting for scan results but it is going to be complicated if we make comparisons and it is going to take a little time to find out what is going on and if there is further damage to the same knee," he added.
If the scans showed a tear in his knee, Vaughan might well be ruled out of the entire tour.
"If there is a tear it would be pretty bad for him," Gregory said. "Usually with such tears you need an operation.
The first Test in Multan begins on Saturday.
England reduced Pakistan 'A' to 31 for one after setting them a victory target of 245 on day two of the three-day tour match.
