PARIS—Novak Djokovic, who beat Rafael Nadal in Roland Garros for the first time on Wednesday, will play Andy Murray in the semifinals. The two have known each other since they were teenagers.

“Semifinals of Grand Slam, playing one of the biggest rivals and the guy I have known for a long time, and I'm sure both of us will get on the court with the intention of winning,” Djokovic said. “I know his game. I'm going to try to prepare myself well.”

Since Murray beat Djokovic in the 2013 Wimbledon final, the Scot has lost the last seven times they've played. Murray underwent back surgery at the end of 2013 and has admitted that his recovery has been slower than expected, saying he didn’t feel 100 percent until this year. In 2014, he played Djokovic four times, only managing to win one set against him.

This year, Murray and Djokovic have met three times, with the Serb winning the Australian Open final in four sets (he won 6-0 in the final set), at Indian Wells in straight sets, and in Miami in three sets (winning 6-0 in the third set). Djokovic currently holds the edge with an 18-8 head-to-head record, but the two have only played on clay twice, at Monte Carlo in 2008 and in Rome in 2011.

However, Murray has won 15 matches in a row on clay, including Munich, the Madrid Masters, and five matches in Paris. He also won his first-round match in Rome before pulling out, citing fatigue.

“He has improved on clay, no doubt about it,” Djokovic said. “I watched him a little bit in Madrid, and Rome, as well, where he retired [after] his match,” said Djokovic, who is 40-2 this season. “Here he's been playing some really good tennis. He's moving better, serving very well, and he always had a touch, one of the best groundstrokes in the game for last ten years since he's been really playing. He's extremely talented."

In addition to his skill, Djokovic had plenty to say about Murray's match-hardened mentality.

"He's also a great fighter and somebody that has a lot of experience playing in big matches. The furthest he got in Roland Garros was semifinals, and I think he played last year semis against Rafa, so I'm sure that he's very motivated to get at least one step further.”