United crashed out of the Champions League after only beating Bayern 3-2 at Old Trafford.
“He was pressured into giving it by the Bayern Munich players, everyone can see that,” Fletcher told Sky Sports.
“He decided he wasn’t going to give it, then he was pressured into it.
“He’s (Rafael) young and he’ll learn from it. He’s got a great future ahead of him and he’s going to be a great player and a big asset for Manchester United.
“He’ll bounce back, he’s a strong character.”
