Novak Djokovic shakes off a back problem and reaches the 4th round of the US Open at 38

Novak Djokovic shakes off a back problem and reaches the 4th round of the US Open at 38

Djokovic pulled away to win 6-4, 6-7 (4), 6-2, 6-3, helped by hitting 18 aces in what he said was his best serving performance of the tournament. The 24-time Grand Slam champion seemed in jeopardy of matching his earliest exit in Flushing Meadows when he needed medical attention near the end of the...