Jose Mourinho was disappointed with Manchester United's "sloppy" attack after the 1-1 draw in Anderlecht on Thursday night.
Henrikh Mkhitaryan's opener was cancelled out by Leander Dendoncker's late header in the Europa League quarter-final first leg, despite Mourinho's side dominating the game.
Mourinho criticised his side's attack, and said if he was a United defender, he would be "upset" with the players up the pitch.
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"The result is positive. To play at home with an advantage, starting the game with an advantage is good, it is a good result in any case.
"But I think the result should be much better, and we can only blame ourselves, because we had an easy game to play in the second half, and we didn't play in attack with that instinct.
"We lost the ball easily too many times, we stopped our counter attacks because of sloppy decisions, sloppy touches on the ball, and then we gave them opportunities to have some counter attacks.
"Luckily our defenders were very much in the game. If I was a Man Utd defender I would be very upset with the attacking players, because they had to kill the game and they didn't."
Paul Pogba missed a clear-cut chance just before Anderlecht's equaliser, striking against the goalkeeper from 12 yards after being set up by Zlatan Ibrahimovic.
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But Mourinho was more upset by his side's lack of instinct in the final third, rather than any major chances that fell to the attacking players.
"I would say it was a strong performance by the team from a defensive point of view. I think Mkhitaryan, Rashford, they did defensively what we asked them to do.
"We were very solid defensively, and that is not just about defenders, it's about the team.
"But it's not just about the chances we missed, because we didn't miss many. It's about the half chances, because the space is there, the time is there, but the end decision is not.
"The decisions were wrong, and probably the only one where everything was correct, the timing the decisions, was Paul's shot. It was a good save by the goalkeeper, but this is what happened to us all season, we have chances but don't score goals."