Akmal was hit hard when he tried to play fast bowler Dilhara Fernando's short pitched delivery on Sunday and retired hurt. He was visibly in pain when he returned to the crease at the fall of sixth wicket before left-arm spinner Rangana Herath bowled him for 24.
Pakistan team management say X-rays showed Akmal has a hairline fracture and it is uncertain if he'll play Monday.
It will be a major setback for Pakistan if Akmal is ruled out as it trails 1-0 in the series. Taufeeq Umar gave away 10 byes in Akmal's absence on Sunday evening.