Manchester United boss Ruben Amorim conceded that repeated lapses in concentration are undermining his team's progress after Monday's chaotic 4-4 draw with Bournemouth at Old Trafford.

Amorim cheered what he thought was the winner when Matheus Cunha scored in the 79th minute for a 4-3 lead. But 19-year-old substitute Eli Junior Kroupi equalised in the 84th minute, the second time in the match United had forfeited the lead.

In one of their best performances this season, United still conceded four goals.

"It's really disappointing, we are really disappointed," Amorim said.

"The result should be completely different. Again, six minutes of the second half, similar to Nottingham (Forest, a 2-2 draw), we lost the concentration, and they score two goals. But we managed to get back to the game, we scored two goals again, and then we have to finish the game."

Amorim's men pummelled the visitors with 17 shots in a thoroughly dominant first half, but Bournemouth were able to capitalise on United's wastefulness.

"We dominated and created so many chances. We had to go to halftime with a different result," Amorim said. "In the end we deserved more.

"People especially at Old Trafford want to win but they want to be inspired to see a team play good football. We did that well in certain moments.

"It was a good performance but we need to be more clinical because created so many chances."

The Portuguese coach stressed the issue is more mental than tactical.

"(There were) A lot of good things, but a lot of things to work on," Amorim said. "We are not winning games sometimes in the details. It's not because it's a back four, back three, back five. It's the details that we need to work, understand the momentum of the game and we need to be clinical."

Amorim tweaked his favoured five-man defence for Monday's match, pushing Amad Diallo, who headed in from close range in the 13th minute, into more of an attacking position.

"You could see straight away in the dressing room, everyone was really disappointed," Diallo said.