Manchester United manager Erik ten Hag said his side had failed to maintain their intensity in Wednesday's 1-1 Europa League draw with FC Twente and should have pushed to kill the visitors off before they had the chance to equalise.
Danish midfielder Christian Eriksen put United ahead in the first half at Old Trafford but was at fault for Twente's equaliser in the 68th minute.
Bart van Rooij's driving run into United's half was halted by an excellent tackle from Manuel Ugarte with the rebound falling to Eriksen, whose lapse of concentration allowed Dutch striker Sam Lammers to steal the ball and score.
"We kept them alive, we were 1-0 up, controlling the game," Ten Hag told reporters. "You have to be consistent and keep going in the second half, we dropped the level and gave the goal away.
"We didn't finish it off, we had to go for the second goal and so they stay alive and we get punished with a mistake from ourselves."
While Eriksen will rue his error, Ten Hag said the whole team shared responsibility for the equaliser.
The goal, it's (a) team (mistake), a player of Twente can dribble through almost the whole pitch, or half the pitch, without stopping," he added.
"That is not acceptable, we can't give a goal away like this. We have seen, again, you have to keep going for the whole game; once you are 1-0 up you have to keep going and go for the second (goal)."
United next host Tottenham Hotspur in the Premier League on Sunday before returning to Europa League action on October 3 with a trip to FC Porto.