Novak Djokovic powered his way into the semifinals of the Monte Carlo Masters on Friday with a 6-0, 6-3 win over U.S. Open champion Marin Cilic.

The Serb, who has dropped only 12 games this week at the Country Club, extended his unbeaten record over his Croatian rival to 12 matches in another display of solid tennis.

Djokovic won the first eight games before Cilic managed to hold his serve, raising a thumb in the air in relief.

The eighth-seeded Cilic fought hard and saved two match points in the final game but could not hold his serve as Djokovic closed out the match.

Djokovic, who ended Rafael Nadal's reign in Monte Carlo when he won the clay-court Masters tournament in 2013, could face the Spaniard in semifinals if he beats David Ferrer later Friday.

Djokovic is off to his best start since 2011 and is bidding to win a third Masters title in a row this year following his victories in Indian Wells and Miami.

Earlier, Tomas Berdych advanced to the semifinals for the third time after Milos Raonic retired with a foot injury.

Raonic called a trainer after dropping serve for the second time to trail 5-2 in the first set. Following a short discussion with the doctor, who had a close look at his strapped right foot, the big-serving Canadian went to see Berdych on the other side of the court to inform him of his decision to give up.

Berdych, who lost to Nadal in the semifinals in 2007 and was stopped by Djokovic three years ago, will next face 14th-seeded Gael Monfils of France. Monfils followed up his convincing win over Roger Federer in the previous round with a 6-1, 6-3 defeat of ninth-seeded Grigor Dimitrov.

Berdych has yet to lose a set this week at the clay-court Masters tournament.

Monfils, who decided to play at the last minute this week after recovering from a right hip injury sooner than expected, was in control as he progressed to the semifinals for the first time.

The Frenchman got off to a strong start and dictated from the baseline to convert his three break points in a 24-minute opening set. Dimitrov was better at the start of the second set but Monfils fended off two break point in the third game with consecutive winning serves, then held after a superb rally punctuated by a cross-court winner just behind the net.

Monfils then broke for a 3-1 lead and sealed his win after Dimitrov could not return a forehand attack.