Novak Djokovic’s French Open title defense — and his hold on the No. 1 ranking — are still alive thanks to a 7-5, 6-7 (6), 2-6, 6-3, 6-0 comeback victory over 22-year-old Italian Lorenzo Musetti in a third-round match that lasted 4 1/2 hours and did not conclude until Sunday after 3 a.m., the latest finish in tournament history.