Nigel Clough heaped praise on to his players, following Sunday's dramatic 3-1 last 16 success over Nottingham Forest.
Jamie Paterson headed the visitors in front, but after Conor Coady had equalised, two late goals, including one from the penalty spot, from substitute Chris Porter ensured United would face with Sheffield Wednesday or Charlton Athletic in the quarter-finals at Bramall Lane next month.
On the game, Clough felt his side were good value to progress to the last eight of the world's most famous club cup competition.
He remarked: "It isn't just a tremendous result, it was an excellent performance. Even at 1-0 down at half-time we told the players to keep going and believing and they did.
"Over the course of the game we just about deserved the win, Forest put us under a lot of pressure at 1-1. They have got a lot of quality and let's not forget they were 16 games unbeaten ahead of this one.
"We were worried when we fell behind, but we didn't chase the game too quickly and our patience was rewarded with the equaliser, which set up an intriguing last 25 minutes because both teams wanted to find a winner."
When asked about the draw for the quarter-finals, which was made at Wembley during the first-half of Sunday's encounter, the Gaffer joked:
"We told the players the news of the draw at half-time, just as we were about to go out for the second-half. We thought about it, then just thought 'what the hell' and told them.
"Some of the lads didn't believe us anyway so when they came back in after the game we told them it was Brighton or Hull away!"