Sead Kolasinac has become an important part in Arsenal squad with his valuable wing-back role.
Emery planned to use the Bosnian defender from the start against Southampton but was forced to change his plans just before the squad set off for the match.
Though Kolasinac took part in the training, reportedly, he complained and medical stuff decided not to put him under risk at St Mary’s.
Meanwhile, Laurent Koscielny did start against Southampton Arsenal medical director with Dr Gary O'Driscoll revealing that the player's time out injured could potentially prolong his career.
"His speed, his pace, his agility, his endurance.
"So, while we can’t say for certain that he’ll come back, with all our markers at the moment there is no deficit there whatsoever at this stage.
"And in fact, in certain areas he’s looking stronger.
"His attitude is so positive, we’re all so positive and there’s no reason to believe whatsoever that he can’t become the player he was, if not better."