Sarfaraz was struck on the back of the head by a bouncer from Asitha Fernando off the very first ball he faced in the afternoon session of the third day's play - it was the first ball with the second new ball and Sarfaraz had stepped down the pitch to it. The ball went for four leg byes.

Sarfaraz underwent a concussion test as per regulations and resumed, batting without any apparent effect for another five overs. He hit three boundaries in that period but after the last, an elegant clip off a full delivery off Dilshan Madushanka for four through midwicket, he called for the Pakistan physiotherapist Cliffe Deacon and gestured to the back of his head, where he had been struck. After a couple of minutes, he walked off.

Concussion substitution regulations require an official assessment of concussion to be provided to match officials and it was duly given to the match referee David Boon. "Sarfaraz Ahmed has been replaced by Mohammad Rizwan as a concussion substitute in the ongoing second Test between Pakistan and Sri Lanka at the Singhalese Sports Club after match referee David Boon accepted the Pakistan team management's request for the substitution," a PCB statement said.

"Sarfaraz was hit on his head while ducking a bouncer by Asitha Fernando in the afternoon session on day three. He remains under the observation of the Pakistan Cricket Board's medical panel."

Rizwan will now be allowed to bat in this innings and is a like-for-like replacement as wicketkeeper-batter. Until this year, Rizwan had been Pakistan's first-choice Test wicketkeeper for a few years, keeping Sarfaraz out of the XI. But a lean run of form with the bat allowed Sarfaraz to return for the home series against New Zealand earlier this year and he duly cemented his place with scores of 86, 53, 78 and 118 in the two Tests.