Three-time winner Djokovic, who is halfway to the first calendar Grand Slam in 47 years, on Friday dropped the first two sets of his third round clash against American 28th seed Sam Querrey 7-6 (8/6) 6-1.
But after just 73 minutes of action, rain sent the pair running for cover off Court One, giving 12-time major winner Djokovic welcome sanctuary before play was called off for the day.
By the end of on Friday, which had seen just three hours of action on outside courts, only 15 of the scheduled 32 ties had been completed.
That led organisers to decide that for the first time since 2004, and only the third time in history, play will take place on the middle Sunday.
Djokovic, who has an 8-1 record over Querrey, has made at least the quarter-finals on his last seven visits to Wimbledon since losing to Marat Safin in the second round eight years ago.
In contrast, seven-time champion Roger Federer had the advantage of playing under the Centre Court roof and became the first man in the fourth round thanks to a 6-4 6-2 6-2 win over Britain’s Daniel Evans.