The England international scored from a well taken free kick as Manchester United earned a 0-1 away victory against Celta Vigo on Thurday.
The 19-year-old striker's curling effort not only gave United the lead, but also a precious away goal going into next Thursday's second leg at Old Trafford.
With United outside the Premier League's top four - a point behind Manchester City and four off third-placed Liverpool - the Europa League perhaps represents their best chance of earning a place in next season's Champions League.
They looked to have spurned their best chances in northern Spain - three times they were denied in the first half by home goalkeeper Sergio Alvarez.
As Vigo improved, United's wastefulness seemed increasingly important, only for Rashford to produce the sort of quality needed to beat the excellent Alvarez.
Returning home with a lead, Jose Mourinho's side will be strong favourites to progress to face Ajax or Lyon in Stockholm on 24 May in the final of a