Erik ten Hag said Manchester United "will give everything" to stop Manchester City replicating their 1999 Treble after reaching the FA Cup final.
City have the Premier League title, the Champions League and the FA Cup in their sights this season, but will have to beat neighbours United in the FA Cup final on June 3 if they want to win all three trophies.
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And Ten Hag, who watched United win a dramatic FA Cup semifinal shootout against Brighton on Sunday, has reassured fans they will do everything to stop City winning the cup and with it preserve United's record as the only English team to win the Treble.
"We will give everything and when I say everything, that is everything, more than 100 percent you can't do, the fans can rely on that." Ten Hag said. "We want to give that against City, we want to give the fans that. "We have to play the perfect game, it was the perfect game we played this season, we have to go again, we know that.
"But first of all we have to focus on different occasions because we have to be in the top four."
After overcoming Brighton at Wembley, Ten Hag also had praise for the character of his team, particularly after their Europa League exit to Sevilla on Thursday.
David De Gea bounced back from a poor display in Spain to make key saves while Marcus Rashford and Jadon Sancho scored in the shoot-out after both missed in England's European Championship final defeat to Italy in the same stadium on 2021.
"David played a great game, in and out of possession, he made some great saves, he's done that so often this season, great saves," Ten Hag added. "We have the most clean sheets in the Premier League, today a clean sheet as well, because we were so determined, we were fighting for it, we were organised.
"They had chances, we had our chances as well on the transition and in direct play and we're happy with that. From Rashy and Jadon about penalties, we knew that, but we knew also they're comfortable on penalties, they dealt with it, it's a time ago, but they are so calm and composed in training with penalties.
"I know this is a different occasion, but I think it's great they had this experience now and I think it will help them for the future. I don't think there's a hesitation, before there was never a hesitation because they are really good penalty takers."