Nine-time champion Rafael Nadal advanced to the semifinals of Roland Garros while defending champion Novak Djokovic fell to Dominic Thiem on Wednesday.

Rafael Nadal advanced after Pablo Carrreno Busta was forced to retire with Nadal ahead 6-2, 2-0. Carreno Busta received treatment on what appeared to be an abdominal injury at the end of the first set. He tried but was unable to continue after two games into the second set.

With the win, Nadal advances to his 10th Roland Garros semifinal and has lost just 22 games in the tournament thus far. It was the first time Carreno Busta had reached the quarterfinals of a major.

Nadal said afterward, “Obviously wasn't the perfect way to win, especially versus a friend. Tough when these things happen but he had a great event.”

Nadal will face Dominic Thiem in of the semifinals.

Thiem rolled past Novak Djokovic 7-6, 6-3, 6-0. The 6-seed had served notice that he would be a factor after becoming the only player to defeat Nadal on clay this year. And while Djokovic defeated Thiem in their last meeting, earlier this spring, there was no hangover from that loss.

It was clear, early in the match, that Djokovic was not at his typical top-level. The world number 2 had two set point opportunities in the first set but could not capitalize.

In the second set, Djokovic had problems with his footwork, slipping and falling on the court. And 35 unforced errors to just 18 winners in the match were part of his undoing on this day.

Meanwhile, Thiem continued has terrific results on clay. “It's amazing for me,” he said. “To beat him for the first time in the quarters of the French Open is a dream.”

Asked about playing Nadal in the semifinals, Thiem responded, “You have to play the best guys round after round,” he said. “It's not getting easier on Friday.”

Nadal owns a 4-2 head-to-head record against the Austrian but Theim won their last meeting, two weeks ago in Rome.