Novak Djokovic, of Serbia, stretches to return a shot from Tennys Sandgren during the third round at the Western & Southern Open tennis tournament, Aug 25, 2020, in New York. (FRANK FRANKLIN II / AP)

Top seeded Novak Djokovic made quick work of Tennys Sandgren on Tuesday, never dropping serve en route to a 6-2 6-4 win over the American to advance to the quarter-finals of the Western and Southern Open.

Next up for Novak Djokovic is German Jan-Lennard Struff, who outlasted David Goffin 6-4 3-6 6-4 earlier on Tuesday

The Serbian converted three of his nine break point opportunities as he extended his win-loss record to 20-0 this year.

“All in all it was just a great performance,” he said.

“I felt better and I played better than I did last night. Everything is going in the right direction.”

Sandgren’s hapless plight was summed up during an exchange in the first set. Having noticed that Djokovic was about to hit an overhead smash, Sandgren turned his back to the net to signal he had surrendered the point. Within a flash, however, Djokovic’s thunderbolt smash had knocked the racket out of the American’s hand.

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Tennys Sandgren returns a shot by Novak Djokovic, of Serbia, during the third round at the Western & Southern Open tennis tournament, Aug 25, 2020, in New York. (FRANK FRANKLIN II / AP)

While a startled Djokovic immediately held up his hand to apologise, a bemused Sandgren leaned over to pick up his racket.

Next up for Djokovic is German Jan-Lennard Struff, who outlasted David Goffin 6-4 3-6 6-4 earlier on Tuesday.

The ATP Masters 1000 event is being played at Flushing Meadows in New York instead of Cincinnati due to the COVID-19 pandemic.