Michael Carrick admitted Manchester United’s Carabao Cup capitulation against Brighton that was greeted by boos at Old Trafford was unacceptable and that answers had to be found at Fulham on Sunday.

United were knocked out 3-2 by Fabian Hürzeler’s visitors after leading 2-0 after 10 minutes through Shea Lacey and Mason Mount. Goals from Charalampos Kostoulas in first‑half added time, Pascal Gross on 65 minutes and Maxim De Cuyper four minutes later eliminated United.

It was the first time United had lost after leading 2-0 at Old Trafford for 50 years and the first time since 1984 they had been defeated there after being ahead at half-time.

Carrick’s side have beaten only Ipswich in the league and Sabah in the Champions League. “Under pressure? That doesn’t bother me one bit,” he said.

“I understand what goes on and how the world works. What bothers me is winning games and I believe we will do, but we have to do it pretty quickly. We can’t accept that [the manner of the defeat] as a group. I take responsibility for it. The performance towards the end of the second half, that’s on me. We have a big game on Sunday that we have to prepare for. We’re out of this competition and we have to go back to winning football matches. It doesn’t feel good at the moment.”

Carrick said of the boos at the end: “I totally understand the feelings of the supporters.”

The manager was asked about JJ Gabriel, the 15-year-old academy player who has informed United he wants to leave. “We have to be a little bit careful on that one. He’s a 15-year-old boy. It’s more about the welfare, the care and the attention of JJ as a child really,” Carrick said. “He’s certainly a young man. The situation is what it is, but we have to be careful about the exposure and how much we jump on that.”

Hürzeler, who made six changes, was delighted with the win. “I am not sure how many players on the pitch had experienced winning here, we have a lot of newcomers but when we play to our level we can compete with anyone in the league,” the Brighton manager said. In the next round his side will travel to the winner of the game on Thursday between Manchester City and Norwich. “We want to go as far as possible but if you want to win something you have to win at the highest level,” Hürzeler said.