Zverev overcomes sluggish start, advances to round of 16 following Sock's retirement

Alexander Zverev has booked his place in the fourth round at the US Open, moving past a resurgent Jack Sock who was forced to retire due to injury in the fourth set.

Zverev secured a 3-6 6-2 6-3 2-1 victory over Sock, who has slowly been rediscovering the form that saw him capture the ATP Masters 1000 title in Paris a few years ago. The American was near flawless in the first set, winning 90% of points on his first serve and hitting forehand winners at will. The fans on Arthur Ashe were expecting another upset as Sock quickly won the first set, much to the home crowd's delight.

However, the American was forced to take a medical timeout soon after, and this slowly signaled his demise. Furthermore, Zverev began to develop a rhythm, making Sock move around the court before ending the point with a groundstroke winner.

The fourth seed quickly took the next two sets, and Sock could see the writing on the wall. After an early break in the fourth, the World No.184 threw in the towel unable to compete anymore due to injury.

Zverev will now face Italian Jannik Sinner in the fourth round, as the thirteenth seed defeated Gael Monfils in an intense five-setter earlier in the day.