The 18-year-old was so far down the pecking order that his name did not even appear on the back of the matchday programme against FC Midtjylland last Thursday, when the striker ensured he would never be left off again.
Rashford hit a brace as United won that do-or-die Europa League last 32 second leg clash and remarkably replicated - if not bettered - that display on Sunday, scoring another double as title-chasing Arsenal were overcome 3-2 at Old Trafford.
Those performances have transformed the striker from relative unknown to one of the country’s most feted players - an astonishing rise that has even take his manager aback. Asked if he could have foreseen Rashford’s impact from his training and development squad displays, Van Gaal said: “No, because he was training with the second team.
“Sometimes he could play a part in the 11 against 11 when we simulate the opponent, and then I saw him.
“You can see him in the second team - he was handy with the ball, his dribble was fast and he was also playing on the right and left side in the second team. I put him the striker’s position.
“You shall never know if a player can cope with the rhythm of your team - he needs that chance. He did it very well, but normally I am always convinced the first time is not so difficult because the player is so focused to do what he has to do.
“I am always saying ‘enjoy yourself’ so to make it so easy as possible, without pressure. But now the pressure shall raise for him because all the people shall look at him in another way.
“After four goals, the fans are expecting the fifth goal and that’s not normal because the average is already high.
“But he has certain qualities that he can score in his way and that’s because he sniffs the situation in advance of other players.”
Rashford’s chance, like with so many others this season, was borne out of necessity due to the lengthy injury list at Old Trafford.
Van Gaal has revealed it is set to slightly ease when Watford visit tonight, with Chris Smalling, Matteo Darmian, and Anthony Martial possibly returning.
The latter’s hamstring complaint in the warm-up last Thursday was the catalyst to Rashford’s surprise first-team chance, so the Frenchman’s return could see the teenager drop to the bench.
Quique Sanchez Flores has urged his Watford players not to fall into the trap of taking United’s injury-hit team lightly.
“I don’t like to say to the players, ‘come on boys, now Manchester United are a little bit weak because they have injuries, because they are younger, because they don’t have experience’, no, it is the opposite,” said Flores.
“I try to send other messages to the players, saying take care and don’t relax.
“Yes, they are younger, but they have a lot of passion, and they want to show everyone they are ready to play in the Premier League.
“So, of course we will play a very tough match, and this is the idea we try to translate to the players. Maybe this is not the best XI they have in the squad, but they are playing really, really well.”