's David De Gea
is already among the world's top goalkeepers but the man who knows him best believes he can get even better.
Goalkeeping coach Emilio Alvarez worked with the Spain
international during his breakthrough at former club Atletico Madrid
De Gea linked back up with his former mentor in 2016 when he became goalkeeping coach at United under Jose Mourinho.
Alvarez was one of a handful of the Portuguese's first-team coaches to keep his job and is confident of helping the club's four-time player of the year get even better.
'David is of course the one who plays more and is an important player for the club, but the three of them are doing very well,' Alvarez said.
'With David, we are always thinking about how he can get better and better, and better.
'To be honest, I don't think David will ever stop. He can get even better!'
De Gea's future remains under scrutiny given his contract is set to expire next summer - after the activation of a one-year extension clause.
Such talk does not seem to distract the 28-year-old, though, nor does the competition with fellow goalkeepers Sergio Romero and Lee Grant - something that Alvarez believes is down to the goalkeepers' close bond.
'It is one of the things that, to be honest, I feel really proud and happy about,' Alvarez told MUTV ahead of Sunday's trip to Tottenham.
'The relationship that the keepers have is amazing, between them and also of course with the way they are interacting with the team.
'Maybe the three of them are making the atmosphere happier for the rest.'