Novak Djokovic has acknowledged that he had to dig deep in order to overcome David Ferrer at the quarter-final stage of the Miami Open this morning.

The Serbian made a slow start to the contest by losing the first three games, but he soon found his rhythm to prevail with a 7-5 7-5 straight-sets win.

Speaking after the match, Djokovic is quoted by BT Sport as saying: "I wasn't feeling the ball that great at the beginning, but I knew that I'm going to have my chances if I stayed committed, if I kept on working.

"But I had to earn my points. I had to fight for everything that I got tonight on the court, because he wasn't going to give it to me. I knew that coming onto the court.

"I knew that he's a great competitor, that he grinds a lot, runs, and makes you play always an extra shot. That's why he's been top‑10 player for so many years and he's tough to beat."

Djokovic will now face John Isner in the final four of the competition.