Madrid visit Dortmund for their UEFA Champions League quarter-final second leg with a place in the last four all but assured following last week's 3-0 win at the Bernabeu.
After notching his 14th Champions League goal of the season in that victory, Ronaldo sat out his side's trip to Real Sociedad on Saturday due to a knee injury, and then reportedly limped out of training in Germany on Monday.
And with a nailbiting La Liga title race and a likely Champions League semi-final on the horizon, Ancelotti has said the FIFA Ballon d'Or winner will only play at Signal Iduna Park if he is deemed fully fit, while also insisting complacency will not affect his team.
"Cristiano Ronaldo feels that he is at 100 per cent, so we are confident that he will feature," said the Italian. "We will not risk him, though.
"Cristiano always wants to play and I want him to play. But he is a professional and knows when he can't.
"We are close to reaching the semi-finals, it's the biggest motivation you can have.
"We have to play the same way and keep a balance between attacking and defending.
"But we are the best at attacking. We should show that."
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