The Germany star has previously revealed how important the Manchester United manager is to him, after their spell together at Bayern Munich.
Manchester United knew that when they were arranging for Louis van Gaal to take over as manager, they would be bringing in a boss who is respected and admired by many still at the top teams he has managed over the years.
Barcelona, Bayern Munich, and of course the Netherlands international side, the 63-year-old is someone that has made a mark on many great players' careers at some time or another.
And coming alongside reports that United are interested in recruiting him this summer, according to the Mirror, Bayern Munich forward Thomas Muller is one such player to champion Van Gaal in the past.
“It’s a secret for nobody,” the Bundesliga star was quoted as saying by ESPN last year.
“Louis van Gaal and I have a relationship that goes beyond that which is normal between a player and a coach.
“However, I have a contract with Bayern until 2017."
Seeing as how Muller reacted when substituted by Pep Guardiola in the Champions League semi-final last week, maybe Van Gaal has reason to try and convince the Bayern man that he'll be more appreciated at United.
It was Van Gaal who gave Muller his big chance at Bayern in the two season he was in charge there from 2009 to 2011, and it appears the player has never forgotten it.
The Germany international has been linked with Manchester United in the past, and said last year that he had turned down an 'astronomical offer' to move to Old Trafford in quotes that appeared in the Guardian.
Muller is a World Cup winner now after the tournament in Brazil last summer, and is enjoying a fine season with Bayern Munich where he has scored 20 goals in 45 games.
Still just 25-years-old, the possibility of signing an attacking player with as much quality as the German would be a huge achievement for United, even though he only signed a contract extension at the Allianz Arena this season.