Sri Lanka captain Tillakaratne Dilshan has suffered a hairline fracture of his right thumb and will bat on the final day of the second Test at Lord's in London on Tuesday only if "absolutely necessary", a team spokesman said.
Dilshan himself initially played down the extent of his injury after twice being hit on the thumb by England fast bowler Chris Tremlett while making 193 - the highest individual Test score by a Sri Lankan at Lord's.
However, he was off the field for all of Monday's play, former skipper Kumar Sangakkara leading the side in his absence, and opening batsman Dilshan was then sent for further X-rays.
"He has suffered a hairline fracture," a team spokesman said on Tuesday.
"He will bat only if absolutely necessary."
England lead the three-match series 1-0 after an innings and 14-run victory in the first Test in Cardiff.
They will resume on Tuesday on 149 for two in their second innings, an overall lead of 156, and with time to force a series-clinching victory.
It was not known till Tuesday if Dilshan would be ruled out of the third and final Test starting at the Rose Bowl, near Southampton, on June 16.