Erik ten Hag says he will "not accept a team that is not giving its best" as Manchester United prepare to face Brighton for a place in the FA Cup final at Wembley on Sunday.
It was a result which manager Ten Hag said had left him "really mad".
"We played a quarter-final in Europe, you have to give everything. But we didn't. It is unacceptable," he said.
"As a manager, I cannot accept a team that is not giving its best. I will never accept it. I made them aware of my feelings. They didn't manage the standards of how I manage a team in professional football.
"Even if you don't play at the highest level we still have to win. That is what we have to learn. If we have setbacks, we have to stick to the plan, stick to the game. You have to keep the confidence."
His Brighton counterpart Roberto de Zerbi, meanwhile, said appearing in the semi-final was an "honour" and that his side will play with "emotion".
The Seagulls are seeking to reach the final for the first time since 1983 - when they lost to United in a replay.
"We are excited. We want to play with our DNA," the Italian said.
"Since working in the UK, you understand the importance of the FA Cup. It's special."
'We have to love the pressure'
FA Cup: From marches to captain - Lewis Dunk's Brighton's journeyBrighton are enjoying an outstanding season. In addition to their FA Cup run, they sit eighth in the Premier League with games in hand over their rivals, and are pushing for a place in Europe.
They also defeated United in their only meeting so far this season, a 2-1 win at Old Trafford back in August.
De Zerbi said his players have to learn to deal with the pressure of playing in high-stakes matches as Brighton look to end the season in style.
"We have to love the pressure," he added.
"We have to get used to it. Playing these types of games is an honour and I have no doubts about my team.
"Manchester United are one of the best teams in the UK. If you want to improve and become better, you have to play this type of game.
"We are speaking about Europe, so we need to compete to become bigger."
'This group can do better' - Ten Hag
Manchester United have fond memories of Wembley this season, having beaten Newcastle there to win the Carabao Cup in February.
Ten Hag's side have bounced back from recent setbacks and, following their exit from Europe, will need to do so again if they are to finish the season with two domestic trophies and a top-four finish.
After losing 7-0 at Liverpool on 5 March, the Red Devils beat Real Betis 4-1 in the Europa League and, more recently, they overcame Brentford 1-0 after losing their previous match at Newcastle.
Asked whether some of his players were playing for their future, following the Sevilla defeat and amid , Ten Hag said: "I think we are always playing for our future as professional players.
"Every game is a test, every season is a test, you have to earn the right to wear the shirt. It's [the same] for me as a manager. We are in the same boat."
The Dutchman added: "We know what to do and we need a huge step forward, higher standards, a better performance to beat Brighton, because that's a tough team.
"We know it's going to be a completely different opponent, a completely different style.
"I know this group of players can do better, they've proved it so many times this season. We've made huge progress during the season but we have steps to go. We have a lot of games to play and occasions to prove it."
Team news - Rashford in contention to start
De Zerbi said none of his Brighton players had been completely ruled out for Sunday when he was asked on Friday.
Defender Joel Veltman and forward Evan Ferguson have both been struggling with injuries.
"The situation with their injuries is not clear yet," added De Zerbi. "We have another two days and we have time to understand and analyse the decision."
Forward Marcus Rashford could start for United after he returned from injury as a substitute against Sevilla.
United are also boosted by the return of midfielder Bruno Fernandes, who is available after serving a suspension in the last match.
