Djokovic wary of Murray's form

Paris - Novak Djokovic is wary of Andy Murray's improved form on clay.

They meet in Friday's French Open semi-finals, with the top-ranked Djokovic leading the third-seeded Briton 18-8 in career matches.

But Murray has not lost on clay this season. The two titles he won, at the Madrid Masters and at Munich, are his first on the slow surface.

"He has improved on clay, no doubt about it. I watched him a little bit in Madrid," Djokovic said. "Here he's been playing some really good tennis. He's moving better, serving very well, and he always had a (good) touch."

Murray reached the French Open semi-finals for the second straight year and the third time in his career after beating David Ferrer 7-6 (7/4), 6-2, 5-7, 6-1.

Djokovic meanwhile crushed nine-time champion Rafael Nadal 7-5, 6-3, 6-1.