Novak Djokovic matched Jimmy Connors for the second-longest unbeaten record at an ATP Tour event by beating Chinese wild card Zhang Ze 6-2, 6-1 to improve to 26-0 at the China Open.

Djokovic has won five titles at the China Open in the past six years, excluding 2011, when he did not play the tournament.

Djokovic matched Connors' 26-0 record at the ATP event in Birmingham, Alabama, from 1974-1980, and now only trails Rafael Nadal's 31-0 start at the French Open from 2005-2009.

"I feel very pleasant playing on the centre court," he said.

"I guess as I keep coming back each year with that positive record, obviously gives me more confidence knowing that I played so well in the past on this court."

On the women's side, the US Open finalists from Italy - Flavia Pennetta and Roberta Vinci - both lost in the third round.

Pennetta, the US Open champion, lost to Russia's Anastasia Pavlyuchenkova 3-6, 6-4, 6-3, while Vinci was beaten by American qualifier Bethanie Mattek-Sands 6-1, 3-6, 6-2

Following her triumph in New York, Pennetta announced that she would retire at the end of the season - a decision she reaffirmed on Thursday.

She has one more tournament scheduled next week in Tianjin, China, and could still qualify for the WTA Finals in Singapore, though her loss to Pavlyuchenkova dented her chances.

"There is nothing going to change if I go to Singapore or not. My career is going to be over anyway," she said.

"Of course, is going to be nice to go to Singapore. If I make it, it's OK. If I don't, I go on vacation."

Wimbledon finalist Garbine Muguruza of Spain clinched her spot at the WTA finals with a 1-6, 6-2, 6-1 win over Mirjana Lucic-Baroni.

Men's results:

1-Novak Djokovic (Serbia) beat Zhang Ze (China) 6-2 6-1
Fabio Fognini (Italy) beat 7-David Goffin (Belgium) 6-2 2-6 6-2
Pablo Cuevas (Uruguay) beat Ivo Karlovic (Croatia) 7-6(5) 7-6(7)

Women's results:

5-Garbine Muguruza Blanco (Spain) beat Mirjana Lucic-Baroni (Croatia) 1-6 6-2 6-1
Anastasia Pavlyuchenkova (Russia) beat 3-Flavia Pennetta (Italy) 3-6 6-4 6-3
Bethanie Mattek-Sands (U.S.) beat 15-Roberta Vinci (Italy) 6-1 3-6 6-2

Source: AP