Sane has struggled for form since his big money arrival from Manchester City.
"He [still] is 100 per cent fit. His efficiency is great," he said in a press conference.
"But like other players, he unnecessarily lost the ball a couple of times against Salzburg and in some instances, he didn't quite pursue one-on-ones. There are reasons for it, and we talked about that. He will try to do better next time.
"When he comes on the pitch, he creates a certain dynamic in the team, increases it. In the last couple of games, he has always scored after being subbed in. That's what makes him stand out and he has quality.
"It is obvious that he still needs time after a long injury, and he will get that time. He works hard in training.
"We are pleased with him, but it is important that when he starts a game, he gives a 100 per cent. We are working on that."