The 33-year-old joined the Belgian club on loan until the end of the season in January after falling out-of-favour at Old Trafford under Louis van Gaal.
Valdes, who is a three-time Champions Legue winner, was ordered to train away from the rest of the United first-team squad for most of the season.
However, although some United supporters would have suspected that Belgium international Marouane Fellaini had a role to play in Valdes’s move to the midfielder’s former club, it was a 16-year-old teenager who provided the goalkeeper with some advice.
“I didn’t have time to talk to [Fellaini] because I left really quickly,” Valdes told Derniere Heure.
“We’ll contact each other to talk about the club and the city that he knows very well.
“On the other hand, I had a discussion with Ilias Moutha-Sebtaoui, a young Manchester United keeper who came from Standard and who told me that it was a big club and that I’d feel good here. He wasn’t mistaken.”
Valdes moved to United ahead of Liverpool in Janaury 2015 but failed to dislodge fellow Spain international David De Gea.
The veteran shot stopper made just two appearances for the Red Devils during his disappointing 12-month stay at Old Trafford.
MORE: The latest football news