While wicketkeeper-batsman Liton - hit on the helmet by a bouncer from Shami in the twenty-first over of Bangladesh's innings - was replaced by Mehidy Hasan, Nayeem - smacked on his third delivery - was substituted by Taijul Islam. However, the replacements raised points of discussion with the ICC’s concussion substitute rules clearly stating the "objective of facilitating a like-for-like replacement for the concussed player". As a result, Mehidy - an off-spinner - will not be allowed to bowl during the entire game, though Taijul - a left-arm spinner - did walk in for a bowler in Nayeem.

But all the confusion arose due to a surprising approach by the BCB before the match got underway. Saif Hassan and Mossadek Hossain - both frontline batsmen - had been ruled out of the Kolkata Test much before the match commenced due to their respective reasons. Saif's injury - and thus his subsequent elimination - was certain two days ahead, while Mossadek was forced to leave the squad to attend to a family member as long back as November 11, even before the Test series began.

A concussion substitute was first used in international cricket during the Ashes earlier this year when Marnus Labuschagne replaced Steven Smith mid-way into the Lord's Test. Just days later, however, a second instance of a concussion substitution occurred with Jermaine Blackwood stepping in for Darren Bravo. Earlier in India's home season this year, Dean Elgar had to be taken off during the second innings of the Ranchi Test, with Theunis de Bruyn taking his place.