Top-ranked Novak Djokovic says he isn't sure whether he will play at the Monte Carlo Masters this week, even though his right ankle injury is healing.

The Serb twisted his ankle April 7 during the quarterfinal of the Davis Cup against the United States. Tests showed that the injury is not as serious as Djokovic feared and he's been training with his coach for the past three days. He's scheduled to play a second-round match on Wednesday in Monte Carlo.

He says he's "more optimistic" than he was at the beginning of the week.

But Djokovic, who lost to eight-time champion Rafael Nadal in last year's final, says he can't guarantee that he'll be on the court. He says he'll decide "Tuesday, at the latest."