MONACO (AP) — Stefanos Tsitsipas stayed on course for a third Monte Carlo Masters title after beating a tiring Jannik Sinner 6-4, 3-6, 6-4 in the semifinals on Saturday, handing the Australian Open champion only his second defeat of the season.

The 12th-seeded Greek plays the winner of a later semifinal between top seed Novak Djokovic and No. 8 Casper Ruud, a two-time French Open runner-up.

Sinner, who already has three titles this year, looked in control in the deciding set when he led 4-3 with a service game to follow.

But he called for a medical timeout during the changeover and a trainer massaged his right knee and thigh. Although a smiling Sinner shared a joke with the trainer, things got more serious in the next game when Tsitsipas broke his serve at the fifth attempt to level the score.

Sinner limped a little at the end of the next game and clutched the hamstring area at the back of his left leg, then had both legs massaged. His movement was restricted in the ensuing game, and Tsitsipas clinched victory on his first match point when Sinner’s backhand from the back of the court went long as he struggled for balance.