Rafael Nadal was in imperious form as he defeated Karen Khachanov to book a last-eight date with John Isner at the China Open, while Alexander Zverev earned a classy win over Fabio Fognini.

The Spaniard, playing his first tournament since winning the US Open, displayed the sparkling form that has seen him return to world number one this year en route to a commanding 6-3 6-3 victory.

Nadal had to save two match points in his first-round win over Lucas Pouille, but on this occasion – bar a shaky start to each set – was largely comfortable and swatted away the six break points he faced.

He remains on course for a second China Open title having triumphed in 2005 and will meet Isner in the quarter-finals following the American's dominant 6-0 6-3 beating of Leonardo Mayer.

Speaking about Thursday's win, Nadal said: "[I am] happy about the match.

"I think I played a solid match. Tomorrow will be a tough one against Isner; he's playing unbelievably well. I saw his match today. He played huge. So let's see what's going on tomorrow."

On the other side of the draw, Zverev overcame the challenge of Fognini to remain on a collision course with Nadal, who he has lost to twice in 2017.

The German, seeded second, needed just one hour and 13 minutes to complete a 6-4 6-2 triumph.

Standing between him and a semi-final berth is Russian teenager Andrey Rublev, who sprung a shock on seventh seed Tomas Berdych 1-6 6-4 6-1.