Bruno Fernandes' late penalty was scant consolation as the Blues won 3-1 to set-up an all-London final with Arsenal on August 1.

"Obviously it is a great achievement for us to get there," Chelsea boss Lampard said. "To win a semi is a great thing, to win a final is the thing.

"We don't want to get too far ahead of ourselves but we can certainly enjoy the performance and the result today.

"I'm not sure where it ranks in the season. It is obviously right up there because of the size of the game and quality of the opponent.

"But we have had some good performances this season. We are progressing, we are getting better.

"There are always going to be some bumps but today was a performance of huge character, personality, work ethic, quality, so I'm very happy."

The key moment came within a minute of the second half getting under way as Mount lapped up a wayward Brandon Williams pass and hit a long-range effort that De Gea somehow let squirm through.

Asked if targeting the United goalkeeper was something he had in his mind, former Chelsea midfielder Lampard said: "It wasn't because I've got huge respect for him as a goalkeeper.

"I know people will always home in on keepers when they make those errors because they're critical for them.

"But all I did say to Mason at half-time was that I want to see him strike through balls more.

"He had a shot in the first half, he tried to kind of whip it or bend it and, for me, outside the box against top keepers – and De Gea's a top keeper – you have to strike through them.

"Of course he didn't catch it brilliantly and it goes in, probably down as a mistake.

"But my job is to worry about my players and with Mason I just wanted him to shoot more. Fortunately three minutes after I said it, he did."

Solskjaer has consistently spoken of his unwavering belief in De Gea, who has made a number of errors over the last 18 months and has Dean Henderson snapping at his heels having shone on loan at Sheffield United.

"Obviously everyone has to perform and everyone has a chance every time we perform to stake a claim in the team," the United boss said.

"David knows he should have saved the second goal but that's done now.

"We've got to move, we've got to look forward to Wednesday (against West Ham in the Premier League).

"It's hard for a keeper to make amends, apart from David making two or three fantastic saves after.

"But you see Brandon, for example – the character he shows. He plays a square pass into Mount, he probably feels a bit responsible and the rest of the half he was absolutely outstanding.

"The kid has been out for a while, not played, out with an eye injury and his character and personality out there, he kept going, kept going.

"It's so much easier for outfield players. David showed (his character) in the rest of the game with a few good saves, but he knows he could have saved that one."

De Gea's error all but settled a semi-final that they were already down in, with Solskjaer saying Eric Bailly's first-half injury destabilised United before Giroud's opener.

The defender was involved in a sickening clash of heads with Maguire and was taken away on a stretcher, having initially gone off looking groggy.

"Eric's in hospital," Solskjaer said. "They're going through all the routine checks and the protocols.

"He got a cut in the back of his head as well, so I don't really know from that (how he is). I haven't heard, haven't spoken to the doctor about him.

"But of course that had a big, big impact on the game.

"Eric was playing very well and we conceded just after the restart there, which was very disappointing. Eric was, of course, a big part of not having any chances against us, really."