Former Netherlands international and Chelsea manager Ruud Gullit has slammed Memphis Depay's boisterous off-field lifestyle.
Depay arrived at Manchester United before the start of the 2015-16 season amid much promise as an Eredivisie champion and top goalscorer but the Dutchman has found going tough at Old Trafford.
Gullit said while he is an admirer of Depay's talents, his off-field antics were an unnecessary distraction from football, particularly when the 21-year-old prodigious winger is struggling for minutes and form in Manchester.
"I am a fan, and I will keep my faith in him but he must do something about the fact that he has been labelled the worst buy in the Premier League in 2015," Gullit wrote in De Telegraaf.
"He needs to deliver. He has a lot of qualities, but to fulfil his potential he has to stay low-key in his personal life.
"If you don't perform, you must not turn up in a brand new Rolls Royce and a new Hummer at the training ground."
Depay was an unused substitute in United's 2-1 win at home to Swansea City on Saturday.
Anthony Martial is Louis van Gaal's preferred option on the left, and that is unlikely to change after the Frenchman scored United's first and set up the second.
Gullit said Depay had to commit himself fully to football until he was back in the United team and playing well.
"Memphis should concentrate fully on football. It would be a shame if someone like Memphis is going to be wasted because of all this side stuff," Gullit said.
"He has to make sure they talk about the footballer Memphis. He has to accept criticism as a man and get on with his job as a footballer.
"Don't be satisfied so easily -- if you get three chances and you only score once, you have to accept that you really did not play well.
"At this level, that is not good enough. If you get one chance, you must put pressure on yourself to convert that one chance. That is what the game is about at this level.
"If you don't like [media scrutiny], don't come to the Premier League.
"In England, there are lots of papers. That creates pressure, but it also creates big salaries for the players.
"All you have to do is perform."