Just four days ago few people outside Old Trafford will even have heard the name Marcus Rashford. Now it may be difficult to escape. After two goals on his Manchester United debut to help the team he supported as a boy to a vital Europa League win over Midtjylland on Thursday, the 18-year-old’s introduction to the first team took a further fairytale turn against Arsenal.

Starting his first Premier League match, in one of the division's showcase fixtures, Rashford scored twice with two clinical finishes in less than three first-half minutes. Arsenal, who had been on top to that point, were left stunned. But before the break a man who once trod the same path from Manchester-raised youth product to first-team starter, Danny Welbeck, got his second goal on his second return to Old Trafford with Arsenal.

Rashford, though, would soon return to the fore. While he didn’t score the third, he more than played his part, holding the ball up like a seasoned forward before laying off for Ander Herrera to curl a shot that deflected off Laurent Koscielny and past Petr Cech. It was deserved, too. United were playing with the verve and purpose their fans had cried for with increasing desperation all season. And Rashford’s youthful enthusiasm at the head of the team was fundamental to the transformation.

Still, a makeshift defense of players either out of position, just returning from injury or hugely inexperienced, meant Manchester United again couldn’t keep the backdoor shut. Mesut Ozil quelled the delight around Old Trafford with a volley to quickly reduce Arsenal’s arrears once more. There was, though, to be no way back.

This was Rashford’s day. This was Louis van Gaal’s day. A manager who made his reputation more than 20 years ago on his ability to develop young players may have just been extricated from the toughest period in his career by an 18-year-old.

With his job teetering on the brink, as United’s hopes of a Champions League place appeared on the verge of extinguishing, suddenly he has been revived. That was memorably evident when the Dutchman, usually locked to his sideline seat and an endless pad of notes, stormed forward to the edge of the touchline and remonstrated with the fourth official by mimicking a dive with such commitment that he appeared determined to make a late case for a supporting actor Oscar at Sunday’s Academy Awards. The crowd rose with chants of “Louis van Gaal’s barmy army.”

Having been lambasted throughout the season, it would surely have been music to Van Gaal’s ears. The mood could not be more different from his counterpart in the Arsenal dugout. After reigniting their title challenge with a dramatic 2-1 victory over leaders Leicester City in their last Premier League outing, there can be no excuse for the way Arsenal have thrown away the initiative.

For all the plaudits Rashford and Manchester United should earn, the limp way Arsenal went down to defeat poses huge question marks about their ability to end a 12-year title drought. In particular, their cutting edge has evaporated alarmingly, a factor that led to Wenger dropping Olivier Giroud from the starting lineup.

Giroud had joined the ranks by the end, yet when a desperate assault would have been expected in the closing minutes, Arsenal barely threatened. Given they were going up against  a backline featuring two ball-playing midfielders, Daley Blind and Michael Carrick, a Uruguayan making just his second Premier League start, Guillermo Varela, and a Dutch 18-year-old making his debut, Tim Fosu-Mensah, Arsenal’s failure was substantial.

Wenger’s side now trail Leicester by five points once more, while they dropped three points back of neighbors Tottenham. Next week’s north London derby at White Hart Lane, coming after Arsenal host Swansea, looks like being absolutely pivotal.

For Manchester United, meanwhile, little has fundamentally changed. They remain fifth, although now just three points adrift of fourth-placed Manchester City before their neighbors play their game in hand. But if the team can take the spirit and the more direct, pulsating style of play they showcased on Sunday into the rest of the season then a Champions League place is far from out of the question. At the very least the day-to-day queries over Van Gaal’s future should dissipate.