Petra Kvitova avoids upset at Brisbane International_1

Dual Wimbledon champion Petra Kvitova has avoided becoming another high-profile scalp at the Brisbane International, surviving an early scare to down Russian Anastasia Pavlyuchenkova.

Fifth seed Kvitova of the Czech Republic overcame a nervous start to overpower Pavlyuchenkova 2-6 6-1 6-0 in just over an hour and a half at the Queensland Tennis Centre's stadium court.

World No.7 Kvitova, a former Brisbane champion, was expected to hit the ground running on Tuesday night.

However, another upset loomed when world No.29 Pavlyuchenkova came out swinging against the 2019 Australian Open finalist.

In the end Kvitova found her range to extend her head to head career record against the Russian to 8-4, but former US Open champion Sloane Stephens wasn't so lucky.

Russian qualifier Liudmila Samsonova produced the upset of the tournament to date, defeating world No.24 Stephens of the USA 6-4 2-6 6-3.

World No.129 Samsonova – making her Brisbane debut – will now take on Kvitova in the second round.

Stephens became the latest star to fall at the first hurdle in Brisbane, joining three-time grand slam champion Angelique Kerber and fourth seed Elina Svitolina.

But defending Australian Open champion Naomi Osaka made a winning start to her summer, defeating Greece's Maria Sakkari 6-2 6-7 (4-7) 6-3 to set up a second-round encounter with American Sofia Kenin.

The two-time grand slam champion and former world No.1 took over two hours to overcome the in-form world No.23 Sakkari, hitting 16 aces on her way to the victory.

American eighth seed Madison Keys eased past Czech qualifier Maria Bouzkova 6-2 6-3 and will now face local favourite Samantha Stosur in the second round.

"Sam's always tough," Keys said.

"I think she's beaten me every time we have played.

"It's also hard to play someone who is going to be playing at home and have the crowd and all that."

Meanwhile, wildcard entry and five-time grand slam champion Maria Sharapova is taking on American qualifier Jennifer Brady in her opening round clash on Tuesday night.