And they doubled their lead three minutes into the second half after a quick free-kick from Jeffrey Schlupp to Patrick van Aanholt caught the United defence napping and the left back fired past David de Gea.
The 27-year-old has also starred for United this season but according to Yahoo Sports, United are yet to reward De Gea for his form between the sticks. The Spain global has less than 16 months remaining on his current deal and is once again the subject of interest from hometown club Real Madrid.
The best United news direct to your Facebook timeline: Like our dedicated Manchester Utd Facebook page.
Athletic Bilbao's Kepa Arrizabalaga, 23, has been touted as a potential replacement, but he signed a new agreement at the San Memes, while Thibaut Courtois' situation at Chelsea has also been monitored.
Real are set for a big summer overhaul of their squad, with current No.1 Keylor Navas set to be moved on as Perez does not believe that the Costa Rican is true world class.
"With high-earners Zlatan Ibrahimovic and Marouane Fellaini expected to be off the wage bill next season, that would help Jose Mourinho pay for De Gea's huge rise", Hetherington noted.
Mourinho said recently of De Gea's situation: "The option, it's obvious that we're not going to let the option disappear". Mr [United executive vice-chairman, Ed] Woodward is not on holiday. Of course he's going to try to give him a contract that keeps him here for much longer than that option that of course we are going to execute. Anyone of you would say the same: "David is to keep".