The Portugal captain was left limping in the final minutes of Wednesday's Group B clash in Sofia with an apparent ankle injury following a late challenge by Anicet Abel.
Ronaldo had earlier cancelled out Marcelinho's sixth-minute opener with the second of two spot-kicks, the first of which was saved by Ludogorets goalkeeper Vladislav Stoyanov, before Karim Benzema netted the winner.
However, the nature of the challenge that led to his injury left Ronaldo seething.
"It was an intentional kick and we’ll see [on Thursday] how it is, but it's a little open at the moment,” he is quoted as saying.
"It was a very ugly tackle and it seemed as if we were playing a game of rugby, but the most important thing is we got the three points and are now half-way towards qualifying for the next stage."
Speaking after the match, coach Carlo Ancelotti said of the complaint: "Cristiano has had a knock. It's painful but nothing serious."
