Petra Kvitova won the battle of Wimbledon champions on Monday in Adelaide as she outserved Elena Rybakina -- who has now crashed out early in two tournaments leading into next week's Australian Open.

Two-time Wimbledon winner Kvitova beat the current All England Club champion 6-3, 7-5 in round one, exacting a measure of revenge.

The 23rd-ranked Russian-born Rybakina won their first head-to-head meeting last year in Ostrava.

World number 16 Kvitova never faced a break point in 86 minutes at Adelaide International II, while breaking Rybakina at the tailend of each set to move safely through.

"I tried to play faster than Elena," said Kvitova, who won Wimbledon in 2011 and 2014.

"She played really great (in Ostrava), it was a good match and I know that she's serving really well.

"I was focusing on my serve and I was trying to wait for some chances to break her."

There are two ATP-WTA Adelaide Internationals this month, with Novak Djokovic and Aryna Sabalenka winning the titles in week one.

Former world number one Garbine Muguruza fell at the first hurdle again on Monday, losing to Switzerland's Belinda Bencic 6-3, 6-4, after being beaten by 2019 US Open champion Bianca Andreescu in the opening Adelaide round last week.

Anastasia Pavlyuchenkova, finalist at the 2021 French Open, also toppled out, falling 7-5, 6-4 to Swiss qualifier Jil Teichmann.

It was the Russian's first match in eight months after ending her 2022 season in May with a recurring knee injury.

After losing in round one of the Adelaide International last week, there was no repeat for American Danielle Collins, with the 2022 Australian Open finalist defeating Karolina Pliskova 6-2, 6-4.

World number one Iga Swiatek and third-ranked Jessica Pegula had been due to play this week but both pulled out after their exploits at the United Cup with Poland and the United States respectively.

In the men's draw, Britain's Jack Draper eased past Italy's Lorenzo Sonego in straight sets while American Mackenzie McDonald outlasted another Briton, Dan Evans, 7-5, 7-5.