The German midfielder has found it tough to break into Ancelotti's favoured starting XI and has scored just once in the Bundesliga.
Muller recently admitted he is trying to remain upbeat about his current situation.
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But Manchester United have been long-term admirers of the 27-year-old.
And Hoeness says United made an £85million bid for him in 2016 and feels he will prove himself again soon rather than later.
Carlo Ancelotti with Thomas Muller
"I am not worried about Thomas. Manchester United were ready to pay €100 million (£85m) for him a year ago," he told Sport Bild.
"But of course, I do hope that he will soon be an undisputed starter again. And I have no doubt that will soon be the case once more.
Bayern Munich's Thomas Muller
"In a normal situation, when Thomas is in form and high on confidence, he will always be a starter at Bayern. He is an absolute key figure for us.
"But I would obviously never put any pressure on the coach to play him."