The Portugal midfielder has so far flopped on-loan at Swansea City this season.
But AVB told BILD: "He can do it, even in Bavaria.
"He is a great talent. But he has to accept the pressure and face the competition. He must be willing to learn, especially from his mistakes.
"If you want to be a great footballer, you have to learn to fight."
AVB continued: "He was the youngest European champion in football history. You have to have patience. I hope the experiment with Swansea takes him further. He certainly has not forgotten his excellent facilities and playing football.
"You need self-confidence, you need support, especially if you're playing abroad so young for the first time. He is not the one we know from Benfica. Renato is nervous, he makes mistakes, he is still a boy. The pressure on a club like Bayern is of course immense."