England captain Michael Vaughan is likely to miss the first Test against West Indies on 17 May after suffering a broken finger during a county game.
He was playing for Yorkshire against Hampshire when he was hit by a rising ball from Australian Stuart Clark.
"Results from the hospital show that he has suffered a fractured finger.
"It looks like he might be out for three to four weeks, but it's too early to say with absolute certainty," said Yorkshire physio Scott McAllister.
"It's desperately bad luck for Michael after the succession of problems he's had to contend with, and we will be monitoring his progress over the next few days," he told the Yorkshire Post newspaper.
Vaughan has not played a Test match since December 2005, having sat out the whole of last summer and the winter Ashes series following knee surgery.
He suffered a hamstring problem after making his comeback during the one-day series which followed the Tests in Australia, but recovered in time to play in all England's matches at the recent World Cup.
The match against Hampshire at the Rose Bowl was Vaughan's first since returning from the Caribbean and he looked in good form making 72 on the opening day.
He was 16 not out in the second innings when he was struck by Clark and forced to retire hurt. The fracture of his right middle finger was later confirmed by x-ray.
If Vaughan is ruled out of the first Test at Lord's, England will face a dilemma over who should replace him as skipper.
Andrew Flintoff led the team in the Ashes Tests, but was stripped of the vice-captaincy for disciplinary reasons during the World Cup and is unlikely to be elevated again.
It may therefore come down to a straight choice between Andrew Strauss, who stood in for Vaughan during last summer's series against Pakistan, or Paul Collingwood.