World No.1 Ashleigh Barty remains upbeat about her Australian Open preparations despite losing her opening match of the season at the Brisbane International on Thursday.

American qualifier Jennifer Brady notched up her first-ever win over a top 10 player when she beat Barty 6-4, 7-6 (7/4) on Pat Rafter Arena.

It was Barty's first match on home soil since becoming world No.1, and came at the venue she trains at and in front of thousands of her adoring home fans.

Barty conceded afterwards she had simply been outplayed by Brady, who also beat former world No.1 Maria Sharapova in the first round.

"Jen was in control of the match - she was in the center of the court being the aggressor and I think you have to give credit where credit's due," Barty, who practiced with Brady early this week, said.

"She came through qualifying, but she's got a ranking that's kind of well below what a lot of people give her credit for.

"She's playing some exceptional tennis, so I certainly can't take that away from her. She played a great match today and deserved to win."

Barty grew up in Ipswich on Brisbane's western outskirts and has had hundreds of fans packing outside courts to watch her practice this week.

But when she was asked whether she felt any pressure because of the attention she insisted she didn't feel any different.

"I think that's [the pressure] all come you from you guys, if I'm being completely honest," she said.

"I think that you guys 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 will now play two-time Wimbledon champion Petra Kvitova, who beat Russian qualifier Liudmila Samsonova 6-3, 6-2.

World No.2 and defending champion had to battle for two hours to avoid the same fate as Barty, eventually beating Australian wildcard Ajla Tomljanovic 6-4, 6-7 (5/7), 6-1.

Pliskova will meet Alison Riske of the US in the quarterfinals.

AFP