Novak Djokovic has said that he is unsure if he will be able to compete in the quarterfinals of the French Open after aggravating a knee injury. Djokovic, who defeated Francisco Cerundolo in five sets to advance, blamed the “slippery” surface at Roland Garros for the injury. "I had slight discomfort in the right knee for a couple of weeks but it was not an injury which was concerning until today... Then I slipped, one of the many times I slipped, and that affected the knee. I started feeling the pain," said Novak Djokovic. Djokovic doesn’t know if “I'll be able to step out on the court and play” in the next round due to the injury but added, “I hope so”. The 37-year-old, who won the game 6-1 5-7 3-6 7-5 6-3, recovered from two sets to one down for the second consecutive round to win. Djokovic recorded his 370th win at a Grand Slam in his career, surpassing great rival Roger Federer and becoming the record holder. The 24-time Grand Slam winner will play seventh seed Casper Ruud, whom Djokovic defeated in straight sets in last year’s final.