UPDATE 1-Tennis-Barty stunned by qualifier Brady in straight sets in Brisbane

World number one Ash Barty suffered a surprise 6-4 7-6(4) defeat on Thursday to American qualifier Jennifer Brady, who claimed the first top-10 win of her career to advance to the Brisbane International quarter-finals.

With the tournament moving into the Pat Rafter Arena at the Queensland Tennis Centre following the end of the ATP Cup group stage, Brady had to contend with not only the Australian top seed, who was given a bye to the last-16, but also a vociferous home crowd. Barty, who had never dropped a set to Brady in two encounters last year, was unable to muster a single break point while the American needed only one break of serve in the opening set before sealing the result in the second set tiebreak.

"I'm very happy to get the win," Brady said. "Ash is obviously a great player and a great person. "It's a little bit surreal. I'm super stoked and I'm shaking a little bit, but I really played well today."

Barty, who exited the tournament in the first round in 2018, struck more winners than Brady but 16 unforced errors opened the door for her American opponent who wrapped up the match in 91 minutes. Despite losing her season opener, Barty remains upbeat about her Australian Open preparations and said she does not feel any extra pressure because of her top ranking.

"It doesn't change the way that I practise. It doesn't change me as a person," she told reporters. "I think that you guys (journalists) enjoy the fact that you get something to write about and you have something to talk about.

"So hopefully I make it interesting for you, but I don't look at it beyond that." Brady, who beat Maria Sharapova in the first round after coming through three qualifiers, will next face fifth seed Petra Kvitova.

Last year's Australian Open finalist Kvitova raced past Russia's Liudmila Samsonova 6-3 6-2 in 61 minutes. Second seed and defending champion Karolina Pliskova had to work hard to avoid the same fate as Barty, as she overcame a mid-match blip to secure a 6-4 6-7(5) 6-1 win over Ajla Tomljanovic.

Third seed Naomi Osaka also had a difficult outing as she came back from a set down to beat American Sofia Kenin 6-7(3) 6-3 6-1.

(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)