Rafael Nadal in quarters

Beijing: 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.

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. 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 Spaniard said he was braced for the “huge” serve of Isner. The in-form American, the sixth seed, is renowned for his booming service game and Nadal expects to come under a barrage on Friday. Isner was impressive in blasting his way past Argentina’s Leonardo Mayer 6-0, 6-3 and Nadal said: “Tomorrow will be a tough one against Isner, he’s playing unbelievably well.

“I saw him today, he played so aggressive, having a lot of success, hitting a lot of winners, returning very well.  Everybody knows that he serves huge and it is so difficult to break him.  But if you add that he is playing very well now from the baseline, he is one of the toughest opponents you can meet,” Nadal added.

Nadal, 31, the top seed and coming off the back of a third US Open title, saved two match points against Frenchman Lucas Pouille in his opener in Beijing. But he was always in control against Khachanov, 21, breaking him in the fourth game of the first set on the way to a routine victory.