Mourinho hopes Depay plays so well at Lyon that United end up buying him back

Expectations were high in the summer of 2015 when the 22-year-old arrived in a big-money deal from PSV Eindhoven, but an underwhelming first season was followed by a difficult second campaign.

Depay has made just one United start since Mourinho's arrival and is now joining Lyon in a deal Press Association Sport understands to be in the region of 25 million euros (£21.7m).

United have inserted a sell-on clause into the deal and an option that could see them one day buy back the winger - a move Mourinho would be welcome to if things work out in France.

Put to the boss that the club have got some security built into the deal if Depay comes good, the Portuguese said: "Of course because potentially he is a very good player.

"I think when Mr Van Gaal decided to buy him, he did well. He knew him very well from the national team.

"He was very young when in the World Cup. He had flashes of top quality.

"He was playing well in Holland - we know that the Dutch league is not the same but he was showing very good things.

"I think Mr Van Gaal and Manchester United they did well to buy him.

"He didn't succeed in this 18 months, I would say, but he is very young so I think it is important for the club to keep control of this talent.

"And we all wish that he plays very, very well at Olympique Lyon and why not to come back because everyone here likes him."

Depay becomes this month's second high-profile departure at Old Trafford after Morgan Schneiderlin joined Everton in a £20million deal rising to £24million.

Like the Frenchman, things have not worked out for the Holland international at Old Trafford - something Mourinho believes in a large part is down to the glut of wingers at his disposal.

"I think it's difficult for me to answer (why it has not work out) because it also didn't work also last season," the United boss said.

"But from my perspective, instead of trying to say why it didn't work, I think it is easier for me and he deserves me to say that he was a fantastic professional.

"So if somebody thinks it didn't work because he was not a great professional, it is totally wrong.

"One thing is some picture that somebody takes with him in an amazing car or dressing in a very specific way, but the image is totally wrong.

"The guy is a fantastic professional, he is a kid that respected everyone, a kid that tried to work hard to get more chances, a kid that was frustrated because he was not having that, but I only have good things to say about him. I think this is much more important.

"If I can find a little reason, it is to say he is a player from one position and the only position where we have overbooking and wingers are what we have more, so it is a position more difficult to have chances."

Depay is to be unveiled by Lyon at a press conference on Friday afternoon and posted numerous updates on Twitter thanking United fans and former team-mates.

"Thanks for all the memories during my time as a Red Devil," he said. "I will never forget all your support at @ManUtd."

Mourinho says he had not been considering selling Schneiderlin or Depay this January, but the United boss says the right offers arrived for players that were "not totally happy" because of their lack of game time.

"I don't think it is human to stop them from going," he said. "Only a bad offer or no offer stops them to go.

"But when the offer is correct, and we know how to evaluate that, I don't think it's human to stop somebody to go.

"So if (the same applies to) one of the players that are not happy, again I would not stop them to go."

Bastian Schweinsteiger, back in the squad but not playing regularly, has been linked with a move to Major League Soccer this month, while it has been reported that Ashley Young is considering an offer from China.

"I don't know because it is media," Mourinho said about Young. "The first time I heard about it was when I was informed that it was in the media.

"I don't give credit to that unless Ashley Young comes and tells me something about it, which he didn't."

Mourinho was similarly coy when it came to questions about January acquisitions.

United head to Stoke on Saturday with a fully fit squad, but Mourinho knows the squad will be tested as they juggle league and cup competitions.

"I always think the best time is the summer market," he added.

"I always consider the January market as an emergency one where you can try and resolve some problems, where you can try to give a little boost to the team for the rest of the season.

"But it is not an easy market. I have to admit that."