Rafael Nadal sent an ominous warning of intent as the 16-time Grand Slam winner bulldozed his way into the quarter-finals of the China Open on Thursday.

The Spanish world number one, enjoying a late-career flourish, dispatched Russia's promising Karen Khachanov 6-3, 6-3 on the outside hard court in Beijing.

Nadal, the top seed and coming off the back of a third US Open title, faces big-serving American John Isner in the last eight.

The 31-year-old Nadal broke Khachanov, ranked 42 in the world, in the fourth game and was never in serious trouble after that.

Khachanov, at age 21 a rising talent, simply had no reply to Nadal's explosive forehand and made too many routine errors.

Nadal broke the young Russian again in the third game of the second set as he cruised into the last eight.  

It was a contrast to his opener in the Chinese capital, when Nadal saved two match points against Frenchman Lucas Pouille.