The former Manchester City star joined Bayern over the summer still recovering from knee surgery he underwent at the start of the season.
Sane has since suffered another injury setback, though Flick insists he's happy with what he's seenn so far.
"It is the case that Leroy had a serious injury, he was injured again in the game against Hoffenheim - so it's normal that you always need a certain amount of time," said Flick.
"But what I'm currently seeing in training is simply good too."
Flick continues: “It is not always easy when you come to the new club and then integrate yourself there directly. That is also due to the situation that we have very few opportunities to train - the things that you normally do in the pre-season."