Novak Djokovic moved within four matches of completing the first men's singles calendar-year Grand Slam in 52 years on Saturday, rallying to beat Japan's Kei Nishikori at the US Open.

Top-ranked Djokovic improved to 18-2 overall against Nishikori, taking his 17th consecutive victory in the rivalry by 6-7 (4/7), 6-3, 6-3, 6-2 at Arthur Ashe Stadium.