Manchester United's Van Gaal struck by rational Rashford

Rashford broke the deadlock in the 54th minute of Wednesday's quarter-final replay, shimmying inside James Tomkins and arcing an unstoppable shot into the top-right corner.

Marouane Fellaini added a second and although Tomkins replied late on, visiting goalkeeper David de Gea brilliantly held West Ham at bay to send United into the last four for the first time since 2011.

Hailing Rashford, who has now scored six times in 11 games, Van Gaal said: "He's very focused on his work and that I admire when you are so young.

"There's so much attention now because he is scoring so many important goals and you can cope with that attention and focus on your next match.

"And when you have criticism, he can cope with criticism also and he can say about himself, 'Yes manager, you are right, and I have to do that and that'.

"I think it is fantastic because there are not a lot of players that can see their self-image in the match."

After months of intense speculation about his position, Van Gaal will lead his side out to face Everton at Wembley later this month knowing that he is two victories from a first trophy as United manager.

The Dutchman came in for a fresh wave of criticism after Sunday's 3-0 defeat at Tottenham Hotspur, but he said that his record meant that he was worthy of the patience afforded him by the United hierarchy.

"I do my work, I do my utmost best and everywhere I have worked, I have won something," he said.

"A lot of things have been changed in all the clubs where I have worked and because of that I am here. I am selected by Manchester United because of that. Not because I am a lousy trainer or manager."

- 'Fighting spirit' -

Van Gaal went on to claim that United had exhibited a similar level of control against West Ham as they had at Tottenham, where Mauricio Pochettino's side struck three times in six second-half minutes, but that the result at White Hart Lane had prevented him from saying so.

"We controlled the game," he said. "But I cannot say that when we lose 3-0. The next day it's: 'Man United has played very lousy.' But it was not true.

"I'm very happy that in spite of that defeat, 3-0, we can have the spirit this evening again like we have showed after the defeat against Liverpool.

"Two-zero in the Europa League against our biggest enemy and the next match was West Ham United and we were 1-0 behind and fighting back (to draw 1-1, in their first meeting).

"You cannot deny that my team has a lot of fighting spirit."

Victory for United meant that West Ham signed off with a defeat in their final FA Cup game at the Boleyn Ground, which they will leave at the end of the season to move to London's Olympic Stadium.

West Ham are vying with United and Manchester City for a Champions League place and manager Slaven Bilic urged his players to shake the disappointment out of their systems as quickly as possible.

"There is always that possibility (that the season will fizzle out), but at the end of the day we are not in a situation in the league that someone can say we have nothing to play for," said the Croatian.

"We have seven big games and we are still big-time in the competition for Europe and we want to finish as high as possible.

"It can affect us tonight (Wednesday) and tomorrow maybe, but then on Friday we have to come together and bounce back. Make no mistake, we're going to do it."