BEIJING, China - No.9 seed Sloane Stephens is back into the round of 16 at the China Open for just the second time in her career, seeing off home hope Zheng Saisai in a confident straight sets victory.

The American had come through a tough battle against Anastasia Pavlyuchenkova in the first round, winning 6-7(8), 6-4, 6-4 to score her first win at an Asian event in three years - her longest win of the year.

That taste of victory has seemed to galvanize Stephens, and she wasted no time in recording another victory - making it her first back-to-back match wins here in five years - and needing an hour and 21 minutes to defeat Zheng 6-1, 6-3.

“I definitely like winning first round, that was my first match in three years I won in Asia,” Stephens told press later. “That can tell you how difficult it is for me on this side of the world. It's nice to be able to win two matches in a row, kind of get it going. I guess every match counts at this point. Just trying to win as much as I can, do the best I can.”

The noon sun cast shadows on the National Tennis Center court, making it difficult to see from different parts of the court. Stephens was unbothered, but Zheng - one of three Chinese women in the second round - recorded double digit unforced errors in the first set.

Stephens didn’t allow Zheng any chances on her serve during the set as she broke early to create a 2-0 lead, and then reeled off the last four games in a row to seal the first tilt in 35 minutes.

Zheng did well to shake off the disappointing first set, coming out of the gates with her first break against Stephens’ serve, changing up her game plan to dish out more slice backhands and dialing up the counterpunching to trouble her opponent.

But her 1-0 lead didn’t last too long as Stephens fired back, converting her fifth break point in a marathon game to level the score. Instead, it was Stephens who was back in the drivers’ seat with her fifth break of the match coming at 4-2, before the American served it out in style to move into the round of 16.

“In general I think I wasn't playing very well,” Zheng admitted later. “I felt she played really fast in the previous meetings, but today with more spin, she played slower. I had many unforced errors. It was really hard to control the ball. I was hesitating. I was trying to adapt to the pace.

“We started rallies from the baseline. I never thought I had the upper-hand advantage against her. I would need more time to adapt to playing against her.”

Currently sitting at No.7 on the Porsche Race to Singapore, Stephens is hoping to seal her first WTA Finals berth this week, and join Simona Halep, Angelique Kerber and Naomi Osaka in Singapore. The American lifted the title in Miami, and reached finals at the French Open and Montreal - losing both to nemesis Halep.

There are five spots left at the WTA Finals after Osaka clinched her spot yesterday following her win over Zarina Diyas.

“I think obviously making Singapore, you finish the top eight of the year, that's a really great accomplishment,” she said. “It’s going to be difficult. Obviously, already I've had a great season, but that would just be like the cherry on top. If I don't make it, there's [Zhuhai], too, which is totally fine.”

Up next, Stephens will take on a spirited big-hitter in her third round match - she awaits the winner between Dominika Cibulkova or Daria Gavrilova.