NEW YORK, NY USA - Playing in the second week of a major for the first time, No.18 seed Wang Qiang stunned No.2 seed Ashleigh Barty 6-2, 6-4 in one hour and 22 minutes to move into her maiden Grand Slam quarterfinal at the US Open 2019.

The Chinese player, who lost former coach Peter McNamara - who had helped her reach the Top 20 last year - to cancer in July, had not been able to win a set from Barty in two previous meetings last year, losing in the Strasbourg quarterfinals and Zhuhai final. Moreover, ranked just No.41 in the Porsche Race to Shenzhen, Wang had made just one semifinal (in The Bronx last week) and two quarterfinals (in Miami and Prague) this season coming into Flushing Meadows. But today, the 27-year-old delivered tennis of the irresistible quality she had shown during last year's Asian swing to hit through Barty and score a career-best first Top 3 victory.

"I think I'm really focused on the court today," assessed Wang afterwards. "I really enjoyed the way I played... I tried to play more patient [than in Zhuhai] today."

The World No.18 also paid tribute to McNamara: "He helped me a lot," she told the press. "Is really tough to me to hear he passed. I think he's always been there with me, yes. He told me how to play the match. He took me to the professional tennis. He always believed in me. He told me I can be the top player."

An authoritative opening service game might have indicated that the Roland Garros champion had come out in top form, controlling points with her slice backhand and finishing them efficiently with her forehand. But Wang swiftly proved herself capable and patient enough to prevent getting herself ensnared in Barty's all-court web. Coolly dealing with the Australian's changes of pace and spin, Wang was disciplined and accurate in her baseline game, only occasionally drawn into error but more often able to redirect the ball around the court to out-manoeuvre Barty.

A booming backhand garnered last year's Nanchang and Guangzhou champion the first break; as the set progressed and Wang's level remained high, it was Barty who seemed rattled as her initial form fell away, racking up 15 unforced errors as she took the ball increasingly late. Uncharacteristically loose mistakes squandered two break-back points in the sixth game; instead, a judicious net foray from Wang put her 5-1 up. Two games later, with Barty failing to execute even her usually reliable dropshots and smashes, marvellous touch on a pickup saw Wang take the opening act on her second set point.

The second set saw much the same pattern continue. The former World No.1 would have her chances to get a foothold in the match, and intermittently showed flashes of her best form - but whenever she appeared to have found some sort of groove, would lapse back into error on the biggest points. Having fallen behind an immediate service break, Barty would carve out one point in the next game, four more in the eighth and another two as Wang served for the match to get back on serve - but was unable to take any, taking her break point conversion rate for the day to zero out of nine.

Afterwards, Barty paid tribute to her opponent's clutch play. "I felt like she was able to put the ball with great depth in difficult positions for me," she said. "I still was able to create opportunities - just very frustrating that on the big points today, Q played a lot better.

"I think I probably missed, on the slice in particular, half a dozen in a standard rally ball where they just float along, just clip the tape. That's frustrating with things like that. It's not missing by massive margins. There were times where I pressed, and I did miss by big margins. Q also forced me to do that with her depth, her depth control a lot of the time."

Wang, by contrast, was resolute in her refusal to give up her lead even when Barty began posting a series of more emphatic service holds. A fierce forehand was followed by a first ace to fend off the early potential turning point; as the set reached its climax, the Bronx semifinalist buckled down to hold firm in the face of dogged Barty defence and a series of challenging extended rallies.

For the most part today, many of Barty's signature shots had let her down - not least her backhand slice, which kept finding the net at inopportune times. But despite tallying 39 errors in total, there were signs towards the end of the match that the 23-year-old was beginning to find some sort of rhythm with her forehand. Saving two match points in the ninth game, and holding two points to level at 5-5, Barty once again seemed on the verge of shifting the momentum. However, Wang rose to the challenge in stellar fashion, eventually taking victory on her fourth match point to become the first Chinese player to reach the US Open quarterfinals since Peng Shuai in 2014. Up next, with a semifinal berth at stake, will be either No.8 seed Serena Williams or No.22 seed Petra Martic.