The Portuguese international has missed the last four games with a hamstring problem, and was forced to track back and defend for spells of the match.
"Ronaldo wasn't in his best shape, but it was important for us that he played. We are happy," Ancelotti told reporters. "Ronaldo sacrificed a lot by playing in a central and defensive position. The whole team has sacrificed a lot."
The former Manchester United star was replaced after 73 minutes by Gareth Bale, who has been suffering with a flu-like illness, but Ancelotti has confirmed that both players will be fully fit for the return leg.
"I had already decided that Ronaldo wouldn't play 90 minutes because he was out for a while," he said. "Bale and Cristiano will both be totally fit for the second leg in Germany."
The two teams will meet in Germany for the second leg on April 29.