Manchester United manager David Moyes admitted his side did not deserve to reach the Capital One Cup final after losing a penalty shootout to Sunderland at Old Trafford.
The Black Cats won 2-1 on penalties after a dramatic conclusion to extra-time to progress to Wembley, where they will face Manchester City on 2 March.
"I am disappointed. We didn't play well enough over the piece," said Moyes.
"If we were going to do it we were going to stumble over the line."
United had lost 2-1 in the first leg at the Stadium of Light, but levelled the tie on aggregate when Jonny Evans headed in eight minutes before half-time.
With no further goals before the end of 90 minutes, the game went to extra-time, where an error by United keeper David De Gea in the 118th minute gifted Phil Bardsley an equaliser on the night - and a goal that would have taken Sunderland to Wembley.
However, Javier Hernandez responded almost immediately when he tapped in from Adnan Januzaj's ball to force spot kicks.
Danny Welbeck and Phil Jones were off target for United and Sunderland goalkeeper Vito Mannone denied Januzaj and then Rafael, with the latter save sending Gus Poyet's side into the final.
But ultimately United paid the price for failing to make the most of home advantage and impose themselves on Sunderland, who dominated possession.
Moyes added: "I didn't think we played well enough on the night. We had opportunities to score a second goal and put ourselves in a better position but we didn't do it.
"It is disappointing but it is part of the job. There has always got to be a loser in a semi-final and it happened to be us.
"I think there have been other games where we have played well enough and not won but I didn't think we played well enough here. The goal was a bit unlucky for David De Gea but, again, we didn't play well enough.
"I didn't think we tried to hang on to anything when we were ahead. I don't think we could have put more attacking players on if we had tried. We had opportunities to finish the game off but we didn't take them."