Manchester United boss Jose Mourinho heaped praise on Marcus Rashford's desire to improve after the 19-year-old's brilliant free-kick handed the English giants a 1-0 Europa League semifinal, first leg win at Celta Vigo on Thursday.

One moment of magic from the England international settled a tight encounter as he pulled his strike across Celta Vigo goalkeeper Sergio Alvarez into the far corner 23 minutes from time.

"The free-kick is work. He works every day. Sometimes the training session finished and he keeps working with my assistant," said Mourinho. "The free-kick is fantastic and I don't think the goalkeeper has any chance because the shot is very fast." Rashford and United could have had more of an advantage to take back to Old Trafford for the second leg on May 11.

Alvarez made a string of first-half saves to deny Rashford, Henrikh Mkhitaryan and Jese Lingard.

However, Mourinho praised Rashford's ability to handle the pressure since Zlatan Ibrahimovic's season was ended by a cruciate ligament injury.

"He worked really hard and created them problems. He had a fantastic shot in the first half that (produced) a beautiful save," added Mourinho. "He is training a lot, he trains, he practises, he enjoys that extra work. Zlatan is not here, that position is not Paul (Pogba's) favourite position and it is a great free-kick.  The ball is very fast, the keeper made a movement and I think it is impossible to stop."

Mourinho hailed a solid overall performance from United that takes them closer to a return to the Champions League next season should they go onto win the competition for the first time. However, he lamented not having killed the tie off given Celta's excellent record away from home in Europe this season. "It is a good result, but it is short," he added.

"It could have been better, 0-1 is a short result and seeing Celta's trajectory in the Europa League they definitely deserve respect."

Celta's frustration spilled over in the closing stages as United ran the clock down efficiently.

And Celta striker John Guidetti said the Spaniards should learn from Mourinho's streetwise tactics. "At the end of the day it's a set-piece that gets us," said the Swedish international.

"After that Mourinho has got a lot of experience and he just tells his players: 'Game's over, game's finished, 1-0, we're not gonna play anymore football tonight'.

"You could see they made 15, 20 minutes (at the end) be three minutes of football

"That's what he does best and it is something we have to learn from." Guidetti, though, believes Celta can take heart from not just their results on the road in the Europa League this season, but also eliminating European champions Real Madrid from the Copa del Rey by winning at the Santiago Bernabeu back in January.

"The Man Utd fans expect more than sitting back and taking a 0-0 draw, so I think we are going to have even more space," he added.

"Last year we scored three goals away against Atletico Madrid to go through (in the Copa del Rey) and their defence is very strong, and this year we won 2-1 at the Bernabeu and they are almost in the Champions League final.