The little finger in Knight's right hand was cracked when he batted in England's second innings on Saturday against pacemen Javagal Srinath and Venkatesh Prasad.
"We are not sure how long he will be out," Dennis Amiss, the Edgbaston chief executive, said yesterday. "It will be a question of monitoring the comfort factor. Batsmen can play with these injuries but it all depends on the degree of pain."
Warwickshire have, however, ruled the left-hander out of their Benson and Hedges Cup semi-final against Northamptonshire at Northampton today.
Knight had suffered a similar injury to his left index finger during Warwickshire's Benson and Hedges quarter-final against Glamorgan on 28 May.
Yorkshire go into the other semi-final, the Roses battle with Lancashire at Old Trafford, with Darren Gough in brilliant form. The England seamer produced his best form of the season to help Yorkshire move to the top of the Championship table by beating Surrey by 221 runs at Middlesbrough.
They took little more than an hour to capture the last five Surrey wickets with Gough returning figures of 4 for 25 yesterday to finish with 5 for 36, on an easy-paced pitch.Reuse content