Early shocks at the WTA Premier event saw No.5 seed Kvitova beaten by Gavrilova while Aleksandra Krunic completed a stunning turnaround against Svitolina.

Julia Goerges required three sets to see off Johanna Konta, while Jelena Ostapenko was also made to work for her 6-4 7-6 (7-3) win over Magdalena Rybarikova.

There were also first-round wins for Donna Vekic and Danielle Collins against Maria Sakkari and Timea Bacsinszky respectively.

The first match of the main draw saw Kvitova suffer the tournament's first big shock, going down 6-2 6-1 to Gavrilova.

Kvitova made a dismal 39 unforced errors and Gavrilova was delighted to have capitalised on the two-time Wimbledon champion's poor showing.

"I think I played a really good match," the unseeded Australian said. "Petra is a really tough opponent and it was a little bit tricky, but I felt like I took my chances and I served really well."

Meanwhile, Svitolina, the No.6 seed, looked on course for a simple victory with a bagel in the first set against Krunic, but she faltered badly from there.

The Ukrainian's commanding lead vanished after Krunic won seven consecutive games from the middle of the second en route to a 0-6 6-4 7-6 (7-4) triumph.

Svitolina was beaten in her first match at the Wuhan Open last week, too, and her loss of form is coming at a bad time with her place in the WTA Finals not secure.

The possibility of a third big shock of the day was on the cards when Goerges was pegged back by Konta in the second set, but she rallied to come through.

Meanwhile, Ostapenko was a break down in the first set before a resurgence against Rybarikova, with a tense second set settled by a tie-break.

Wang Qiang, China's number one, is up next for Ostapenko, however, bringing the promise of another tough test.