Yasir Ali, the debutant batsman was hit in the helmet on Monday while trying to duck a short delivery from Shaheen Shah Afridi.
The incident took place on the fourth day of the first Test cricket match between Bangladesh and Pakistan at the Zahur Ahmed Chowdhury Stadium in Chattogram.
The right-handed batsman was checked as per the ICC concussion protocol.
Although Yasir played four more balls, he felt uncomfortable and left the field. He was on 36 runs at that time.
As Yasir was not able to bat again in the match, Nurul Hasan replaced him as a concussion substitute.
Earlier on the day, Mushfiqur Rahim started the morning with a boundary but after just one ball he was bowled by Hasan Ali.
Mushfiq left the delivery and it dislodged the stumps.
Bangladesh were 115-6 at lunch leading by 159 runs.
Liton Das, who picked his maiden Test century in the first innings, was unbeaten on 32.