Ozil was clearly unhappy when being substituted.
Emery stated: "No, it is normal not to be happy. I like the players like him who show the character when we are not playing well, and when I substituted him at 2-1 usually every player wants to continue playing."
On why he swapped Ozil for Danny Welbeck, the manager continued: "In the last match away in the Premier League, against Fulham, we played like that and did a very good job. I think we lost a little of our possession with the ball and the match was more about the transition, like in our last matches.
"Also, with Danny and Laca, I wanted to find one good transition between two players and also more goals. Also, in free-kicks defensively, they were pushing and put a ninth player on the pitch for free-kicks to find more chances to score. Danny Welbeck is very good in these situations, both defensively and offensively."