Novak Djokovic will have an MRI on his injured right ankle when he returns to his home base in Monte Carlo and considers himself questionable for that city’s Masters tournament, which begins on April 15.

The world No. 1 sprained his ankle in his 7-5, 6-7 (5), 6-1, 6-0 victory over Sam Querrey in Serbia’s 3-1 Davis Cup quarterfinal victory over the United States. Djokovic said that if he was playing a regular tour event, he might not have continued to play.

“I’m a bit concerned definitely,” he said. “It’s not comfortable feeling what I feel right now with that ankle. The nature of the injury is still to be determined. One hour, one hour and a half after the end of the match, all I can say now is it doesn’t look good. So what’s going to happen for me next is to try to first of all diagnose and determine the nature of the injury and how bad it is, and then see from there.

“I was planning to play Monte Carlo. I live there and train there, so it feels like a home tournament to me. I’m going to do everything in my power to recover for that tournament. How realistic it is, to be honest, I don’t know.”