Novak Djokovic boosted by Kevin Anderson victory

Defending Wimbledon champion Novak Djokovic has said that his fourth-round match against Kevin Anderson was "one of the most difficult" of his career.

The 28-year-old came from two sets down to beat his South African opponent and book his place in the quarter-finals at the All England Club.

"Kevin served exceptionally well," Djokovic told BBC Sport. "This was one of the most difficult matches I have played at Wimbledon in my career.

"It was high-quality tennis in the fifth set. At times I was helpless with my return - it was very difficult to read his serve and he was very aggressive.

"I was two sets down and coming back to win gives me great satisfaction and confidence for my next challenge."

Djokovic has won the title at Wimbledon five times during his career.