Jose Mourinho says he apologised to Henrikh Mkhitaryan after taking him off at half-time in Manchester United's win over Derby.
United claimed a 2-0 win over the Championship side in the FA Cup third round on Friday evening.
It was 0-0 at half-time at Old Trafford and Mourinho opted to remove the Armenian in favour of Romelu Lukaku, who provided a goal and an assist late on to seal the win.
Mourinho's decision may have proven to be the correct call on balance but he says Mkhitaryan didn't deserve to be hauled off at the break regardless.
"(It was) unfair. Unfair," he said.
"And I told that at half-time. I didn't like what I did. Unfair. He didn't deserve it.
"He was playing well, he was not playing bad. He had a couple of missed possessions but he was playing well, he was giving (a) good dynamic to the team.
"My feeling was just that (Marcus) Rashford is not going to score a goal. In the moment he's not going to score a goal. And because of that I'm not going to lose time and I'm going to play Romelu.
"And then I had to sacrifice a player and it was Micki the one that I sacrificed.
"But it's something that I normally don't do. I did at half-time. I apologised to him in front of the people because he didn't deserve (it)."
Mkhitaryan has struggled for game time since joining United from Borussia Dortmund and it has been speculated he could be allowed to leave in the January window.
BVB have been linked and Italy's Inter Milan are also said to be keen, but both clubs are reportedly unwilling to match his current salary at Old Trafford.