Wimbledon may have built its reputation on being an uniquely grass-court Grand Slam tournament but defending champion Novak Djokovic is happy to play it under a roof, with the lights burning bright.

Top seed and world No 1 Djokovic gave the Centre Court roof the thumbs up on Wednesday after beating America's Ryan Harrison 6-4, 6-4, 6-4 to reach the third round.

With the roof closed after three hours of rain had brought a halt to action on the outside courts, Djokovic was delighted to get a second chance to play the late-night entertainer.