Once again, Novak Djokovic proved to be too much for Kei Nishikori.
Nishikori was beaten by the Serbian world No. 1 6-7 (4-7), 6-3, 6-3, 6-2 on Saturday at the U.S. Open, preventing him from moving into the fourth round in New York.
The victory at Arthur Ashe Stadium improved Djokovic's head-to-head record against Nishikori to 18-2. Djokovic has won the first three Grand Slam tournaments of the year.
On Saturday afternoon, Djokovic suffered an early break in the first set, then recovered but dropped the tiebreaker.
He was tested by the 56th-ranked Shimane Prefecture native in a match that lasted over three hours, but recovered from the early blip by hitting 45 winners to see off Nishikori in four sets and keep his hopes of a calendar-year Grand Slam and 21st major title alive.
Nishikori entered the tournament unseeded and was mopped by Djokovic in straight sets at the Tokyo Olympics in late July. The 31-year-old Japanese has not beaten Djokovic since the 2014 U.S. Open semifinals.
Nishikori was the last remaining Japanese singles player at the U.S. Open.