Manchester United manager Jose Mourinho blamed his side's "sloppy" attackers after Anderlecht grabbed a late equaliser in the teams' Europa League quarter-final first leg.
United led 1-0 in Belgium until the 86th minute, when the hosts equalised with their first effort on target.
"If I was a Manchester United defender, I would be very upset with the attacking players," Mourinho said.
"They did the serious work. The people who had to kill the game didn't."
Henrikh Mkhitaryan tapped in for United in the 36th minute, but it was the only successful effort of their 16 shots at goal.
The visitors' attack lags well behind the rest of their top-four rivals in the Premier League, having scored only 46 goals. Chelsea, Tottenham, Liverpool, Manchester City and Arsenal have all managed more than 60.
Zlatan Ibrahimovic is the team's top-scorer with 28 goals in all competitions, with Mkhitaryan and Juan Mata the only others in double figures.
"It is the same problem," added Mourinho. "We had control, we had chances, but we do not score enough goals.
"In my poor English, I cannot find a better word than sloppy. You have to play more seriously.
"Put the performance of two or three of our attacking players together and you squeeze not much juice out of it. Marcus Rashford, Jesse Lingard, Zlatan Ibrahimovic, Anthony Martial - they were very similar."
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Phil, Cardiff: Last half an hour the whole United attack just walking around with no desire to break with pace and kill the game off. The fact that they seem to be happy with a 1-0 at Anderlecht says how far United have fallen. And they paid the price with poor finishing as usual this season.
Darragh, Belfast: Same old United this season we go one up and take the foot off the pedal, never look like we're gonna blow a team away! Not great for confidence with Chelsea on Sunday.
Chris Perez: You can spend as much money on a squad as possible but without time they will play as separate pieces of the jigsaw. Jose will make United great again.