Fletcher believes his teenage midfield colleague, who joined United from Crewe in the summer, will benefit from such a tough introduction to the Champions League in Istanbul.
"The experience in Turkey will be massive for Nick Powell's development," said Fletcher.
"You realise in matches like these how quick you have to play the ball, how quick the game is and your touch has to be right.
"You also have to be aware of the tactical side of it and getting behind the ball and doing your job as the manager has told you. No disrespect to Crewe but coming into an atmosphere like that he will take a lot from the game and learn a lot. He will be a better player for it.
"I came to Istanbul as a 20-year-old to play Fenerbahce and it was a very good lesson to learn. It was a real eye-opener. I didn't expect the ferociousness of the crowd and the tempo of the game. Playing in that atmosphere then was a real shock to the system.
"I now know what to expect and have been fortunate to play in a lot of big games in Europe and big atmospheres but that one certainly helped.
"It helps to bring you on to experience that early in your career. It makes you realise what you have to do to play at this level. You have to do things a lot quicker than what you have to in the Premier League.
"The other side of it is the tactical awareness in Europe. He will take it on board."