Germany's Angelique Kerber hits a return against Bernarda Pera of the US during their women's singles match on day one of the Australian Open tennis tournament in Melbourne on Feb 8, 2021. (DAVID GRAY / AFP)

SYDNEY - The Australian Open got underway at Melbourne Park on Monday, with several big names exiting the tournament in the first round.

Former world No 1 and three-time grand slam champion Angelique Kerber suffered a huge first round blow at the hands of unseeded Bernarda Pera 6-0, 6-4, while current-ranked No 11 Gael Monfils continued a string of poor form, losing to 21-year-old Emil Ruusuvuori from Finland 3-6, 6-4, 7-5, 3-6, 6-3.

China's No 1, Wang Qiang also suffered a shock first round exit, losing a marathon battle to Italy's Sara Errani 6-2, 4-6, 4-6

Kerber, who won the AO in 2016, said that undergoing two weeks of hard quarantine prior to the tournament likely played a part in her early exit.

"Of course, you feel it if you are not hitting balls for two weeks and you are not in the rhythm," she said.

"Especially if you play a real match where it counts and you play the first matches in a grand slam, also against an opponent who doesn't stay in the hard lockdown."

China's No 1, Wang Qiang also suffered a shock first round exit, losing a marathon battle to Italy's Sara Errani 6-2, 4-6, 4-6.

Having made a name for herself after beating Serena Williams at last year's event, No 30 seed Wang was unable to maintain match-winning form long enough to progress, requiring medical attention for her leg late in the second set.

ALSO READ: China's Wang departs Australian Open in first round upset

Japan's Naomi Osaka hits a return against Russia's Anastasia Pavlyuchenkova during their women's singles match on day one of the Australian Open tennis tournament in Melbourne on Feb 8, 2021. (WILLIAM WEST / AFP)

Meanwhile, 2019 AO champion Naomi Osaka kicked off her tournament with a comfortable 6-1, 6-2 win over Anastasia Pavlyuchenkova on main-stage, Rod Laver Arena, where later No 2 seed Simona Halep also cruised into round two with a win over Aussie wildcard Lizette Cabrera 6-2, 6-1.

Serena Williams, who is chasing a record 24th Grand Slam, made a convincing run into the second round, beating Germany's Laura Siegemund 6-1, 6-1, while her sister Venus Williams progressed against Belgian Kirsten Flipkens 7-5, 6-2.

In the men's competition, reigning champion Novak Djokovic wasted little time dispatching Jeremy Chardy 6-3, 6-1, 6-2, while fellow 2020 finalist Dominic Thiem bested his first round opponent, Mikhail Kukushkin 7-6 (2), 6-2, 6-3.

World No 7 Alexander Zverev had a more difficult time booking his spot in round two, taking two hours and 42 minutes to dispatch a defiant Marcos Giron from the US, 6-7 (8), 7-6 (5), 6-3, 6-2.

Serbia's Novak Djokovic hits a return against France's Jeremy Chardy during their men's singles match on day one of the Australian Open tennis tournament in Melbourne on Feb 8, 2021. (WILLIAM WEST / AFP)