Djokovic remains unbeaten in China

World number one Novak Djokovic had little trouble reaching the quarter-finals of the China Open after beating China's Ze Zhang on Thursday.

The Serb was way too strong for Ze winning 6-2, 6-1 in 55 minutes to remain unbeaten in the tournament, taking his record to 26-0.

After holding serve in the first game of the match Djokovic broke Ze the next game going on to win the set 6-2.

In the second set the Serb was even more convincing, never looking in trouble on serve, breaking Ze twice on his way to a 6-1 win. 

He next faces American sixth-seed John Isner who got past Australian John Millman 4-6, 7-6(5), 6-4.