World No.1 Ash Barty, Japanese titleholder Naomi Osaka, fourth-seeded French Open champion Barbora Krejcikova, fifth seed Sakkari and Tokyo Olympics gold medallist Belinda Bencic all swept to straight-sets wins on Monday.

But it was Sakkari making the noises following her 6-4 7-6 (7-2) victory over German Tatjana Maria in the first match of the Open on Rod Laver Arena.

"Last year I lost in the first round and then I finished the year in the top 10 so things can change in a week," the Greek said.

"I never used to believe that I belonged but I started working a lot in my mind, on how I can get all these negative thoughts and all this pressure away from me.

"Of course, you can never do like a hundred per cent what you're trying to do, trying to achieve, but you can improve.

"I proved myself that I have a strong mind. Yeah, I proved it on court actually."

The 26-year-old proved it with charges to the French and US Open semi-finals and is now looking to take the next step at Melbourne Park.

Sakkari didn't have it all her own way against Maria, made to sweat against the world No.287 who needed a special ranking protection to make the draw after taking maternity leave last year following the birth of her second child.

"We all know first rounds are not that easy," Sakkari said.

"Credit to Tatjana; she really played a great match. She has a very weird game in a good way. I found it really tough to find my rhythm against her."

Sakkari also admitted to being anxious playing the first match of the 2022 Open on centre court.

"I was a little bit stressed because I was opening up this tournament on this wonderful court. It's a privilege," said the world No.8.

"I'm very glad that I was able to find a way to win and to keep myself in the tournament."

Barty had no such concerns, launching her title assault with a brutal 6-0 6-1 win over Ukrainian qualifier Lesia Tsurenko on Monday night.

Krejcikova conceded only one more game than the top seed in a 6-2 6-0 rout of Andrea Petkovic, while Osaka was untroubled in a 6-3 6-3 win over Colombian Camila Osorio.

Playing only her second event since contracting COVID-19 last month, Bencic powered to a 6-4 6-3 victory over Kristina Mladenovic.

Other day-one winners included 15th seed Elina Svitolina and two-time Open champion Victoria Azarenka, seeded 24th this campaign.

But 2020 champion Sofia Kenin bowed out in a 7-6 (7-2) 7-5 defeat to fellow American Madison Keys.

US teenage ace Coco Gauff, the 18th seed, also suffered a shock 6-4 6-2 loss to Qiang Wang.

Australian Associated Press