BEIJING, Oct. 1 -- A spirited performance from a hometown favourite and a professional outing by the reigning US Open women's champion headlined the action at the China Open in Beijing on Monday.
Defending US Open champion Naomi Osaka saw off a resilient Zarina Diyas 6-4, 6-3.
The two players fought hard in the first set, with both holding serve to 4-all, despite an early break opportunity for the Japanese world No. 8 in Diyas' first service game.
The second set got underway with each player getting breaks, followed by Osaka running away with the proceedings to go up 5-1. Diyas then held serve and replied with a stellar break of her own, but Osaka kept it together on return to seal the match in just over one hour.
"I've played her [Diyas] before in [the] French Open, and it was a really tough match. I think... I needed to find a way to win, even if it was [by] playing ugly," Osaka said.
China's Zhang Shuai is through to the second round after a hard-fought win over Belgium's Elise Mertens.
Zhang beat her opponent 6-1, 3-6, 6-3. Zhang praised the Chinese fans for their support during a difficult game.
"In Beijing and the China Open I am always inspired by the fans, their support, which helps me raise my level in Beijing."
The second set was a struggle for Zhang. She did well at the outset, holding her service games and managing to break her opponent to go up at 2-1. But the turning point came when a Mertens break made it 3-all, and a series of unforced errors helped the Belgian run away with the set.
"I tried to follow my plan, as I did in the first set, but that was not enough. I lost some points consecutively. I made some errors. She hit several key winners. I made changes in the third set. I was more aggressive. I felt the match really started in the third set. It was a great performance from both of us."
Spanish No. 14 seed Garbine Muguruza saw off Ekaterina Makarova 6-0, 6-4 in a one-sided affair.
After not managing to pick up a single game in the first set, Makarova improved in the second, breaking Muguruza's serve to prolong the contest. However Muguruza maintained her composure and was able to see off the unseeded Russian.
In the men's draw, a visibly frustrated Sam Querrey lost 6-4, 6-4 to Karen Kachenov. Querrey cut an agitated figure on the court, as the American could not find a way past his Russian opponent. Querrey made seven double faults and could not get his service game to work.
For his part, Kachenov didn't offer Querrey a single break point opportunity in the first set and even though the American showed more fighting spirit in the second, it would turn out to be too little too late.
No. 2 seed Caroline Wozniacki thundered past Switzerland's Belinda Bencic 6-2, 6-3. It was a dominant performance as the Dane won five consecutive games before Bencic broke serve in the second set. That glimmer of hope proved to be a false dawn for the Swiss player, as Wozniacki immediately broke back to stop any momentum Bencic might have started to find.
Bencic and Wozniacki have met on six occasions and the Swiss player has managed to win four matches. The former world number 1 was in good spirits after beating a potentially tricky opponent.
"It's been a while since I've played her. I think a lot of things have happened since then. I think I just stayed really steady and I tried to stay really focused. That was really it. I tried to not really think about the past matches, just think about this one as a new one, new experience, a new stadium. That was really that," Wozniacki said.
In men's doubles action China's Zhang Ze and Gong Maoxin lost out to Marcelo Melo and Lukasz Kubot. The Chinese pair lost 4-6 ,6-4, 7-10.
In women's doubles, China's Duan Yingying and Wang Yafan lost 6-1, 4-6, 10-7 to Nicole Melichar and Kveta Peschke.
Anastasija Sevastova advanced to the next round after Madison Keys withdrew from the tournament.