Marcus Rashford's brilliant 67th minute free-kick fired United into a dominant position in the tie, yet Mourinho was frustrated that his side failed to make the most of their superiority in Spain to open up a commanding lead heading into the second leg.
However, the fresh concerns to Rashford and Young are the last thing Mourinho needed as they could now join Zlatan Ibrahimovic, Marcos Rojo, Luke Shaw and Timothy Fosu-Mensah in missing the Arsenal game.
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And after important goals against Chelsea and Anderlecht last month, Lingard insists Rashford is proving he can shoulder the responsibility.
"He's been unbelievable and he's come tremendously far", he said.
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And he even waved, with joy clearly etched on his face, as he prepares for his side to take on Watford in the Premier League. He was disappointed not to start but came off the bench to a standing ovation.
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"It's part and parcel of football", he said. But the way we started the game and the way we controlled the game in the first half I thought we deserved a better result. He's going to learn. "It's all about hard work and dedication, you know - he's just got to keep going now". Regarding Rashford, Mourinho said: "He started the game already with a little problem and obviously with the running he was feeling [this]".
"Of late he's been put on set-pieces and his corner delivery and free-kicks have been excellent". Also, we play at Old Trafford, in front of 75,000 people, so we have to give everything on Thursday. "We are going to try (to win). we are not going to Arsenal to say "beat us", or "beat us 5 or 6-0".
"The free-kick is fantastic and I don't think the goalkeeper has any chance because the shot is very fast". Their keeper has no chance.
United are bidding to win the Europa League for the first time and guarantee a place in next season's Champions League in the process.
United's Spanish midfielder Ander Herrera, who hails from the northern Basque region of Bilbao, urged caution though and stressed that Vigo remain a risky side ahead of the second leg.