Rafael Nadal ominously dispatched Karen Khachanov in straight sets to reach the quarter-finals of the China Open on Thursday.

The world number one saved two match points in his first-round victory over Lucas Pouille in Beijing, but sealed a more commanding 6-3 6-3 win over the unseeded Khachanov.

Aside from a shaky start to both sets, Nadal was solid on serve and the top seed proved to be a cut above Khachanov.

The Spaniard, playing his first ATP tournament since winning the US Open, made only 15 unforced errors and broke three times to ensure he will face John Isner in the last eight.

Nadal, the China Open champion 12 years ago, beat the Russian in their only previous meeting at Wimbledon this year and set about a repeat after saving three break points in a troublesome first game.

The 16-time grand slam champion unleashed some fierce forehands and broke for a 3-1 lead, going on to serve out the set after a defiant Khachanov saved two set points courtesy of rasping groundstrokes of his own at 5-2 down.

Three break points came and went for Khachanov in game two of the second set and the 21-year-old did not do himself any favours, serving seven double faults.

A vibrant Nadal piled on the pressure to win against serve for a 2-1 lead and he did not give Khachanov another sniff, wrapping up the win in just shy of an hour and a half.