The Portuguese star was in some discomfort after attempting a bicycle kick in the dying minutes of Madrid's win, and failed to complete a Liga game for the first time this season
Real Madrid's joy at downing Villarreal 3-0 was tempered with concerns over Cristiano Ronaldo's fitness after the forward failed to complete 90 minutes.
The Portugal striker appeared to hurt himself while attempting a late overhead kick during the game, as Madrid kept the pressure on Barcelona and Atletico Madrid.
With Madrid having used up their three substitutions, he went straight down the tunnel into the dressing room, marking the first time this season he has failed to complete the 90 minutes in La Liga.
Ronaldo will now undergo tests on a possible thigh injury, and could be in doubt for the Champions League semi-final against Manchester City.
Zinedine Zidane attempted to play down fears, stating that Ronaldo was better than first feared.
"Cristiano felt something at the end. He went off because he wanted to know what it was," the coach told reporters.
"It looks like more of a scare than anything else. We will have to see tomorrow.
"We are concerned, but after seeing him in the dressing room I am less worried. He is relaxed. It doesn't like anything serious."
Source : Goal