Atletico Madrid took the lead after just 53 seconds when Pablo Barrios finished from close range following Alex Baena’s delivery. United responded by creating several promising opportunities, with Bryan Mbeumo testing Jan Oblak and Marcus Rashford also failing to make the most of a chance.
Carrick’s team continued to threaten after the break, but their hopes suffered a major setback when Leny Yoro was sent off following a VAR review with 16 minutes remaining. Ademola Lookman then scored in the 79th minute to secure the points for Diego Simeone’s side.
Carrick was disappointed that United had failed to capitalise on the chances they created.
“It is a tough enough place to come and to get the start we had obviously puts us in a more difficult situation but I thought we grew into the game,” he said.
“We had four big chances, big opportunities and the game can look very different. They were really good opportunities as well, they weren't just little half ones.”
Manchester United had threatened to equalise before the interval, while Bruno Fernandes produced another opportunity in the second half. However, Oblak and Atlético’s defence held firm before the dismissal changed the contest.
Carrick felt his team had done enough in open play to remain in contention, despite the early setback.
“There's probably not many teams that would come here and have those chances against them [Atleti], so we've done a lot of things good tonight,” he said.
“The game was really close and in the balance, take away that first minute which is a goal — obviously a major part of it — but take away that and we were right in the game going through the second half.”
The United manager also identified defensive details that needed attention, particularly the space Atlético found when switching play. Nevertheless, he maintained that the performance offered reasons for encouragement.
“We feel the game was there for us, is the biggest thing, we could have and should have got more from it.”
The defeat extended United’s winless run to five matches in all competitions, increasing the pressure ahead of Sunday’s Premier League trip to Leeds United.
Carrick insisted confidence was not the problem and said his players remained committed despite the disappointing results.
“I don't see the confidence as being an issue,” he said. “I think to come here and respond and take the ball like we did and control spells and create chances, the confidence is there.”
He added that United had to find a way to turn encouraging spells into victories.
“We need to find a way for sure to produce winning performances again. Tonight is a one-off game, which is very different — it's the Champions League, it's a tough place to come.
“We need to improve certain things, we're doing certain things okay. But we need to win games, for sure.”