Serena Williams launched her latest bid for a record-equalling 24th Grand Slam with a 56-minute demolition of Laura Siegemund at the Australian Open.

The American, 39, said it was "vintage Serena" as she thrashed the German 6-1 6-1 in front of a small, unmasked crowd on Rod Laver Arena.

US Open champion Naomi Osaka also made a convincing start with a 6-1 6-2 win over Russia's Anastasia Pavlyuchenkova.

But former champion Angelique Kerber was the first seed to be knocked out.

The German 23rd seed, who was one of 72 players to spend 14 days in 'hard' quarantine before the tournament - confined to a hotel room and unable to train outside - was beaten 6-0 6-4 by American Bernarda Pera.

Kerber, a three-time Grand Slam champion, said the quarantine had affected her form for the major.

"You feel it, especially if you play a real match where it counts and you play against an opponent who doesn't stay in the hard lockdown," she said.

American 24th seed Alison Riske, who also did the hard quarantine, lost 6-2 6-1 to Russian world number 101 Anastasia Potapova.

French Open champion Iga Swiatek raced into the second round with a 6-1 6-3 win over Arantxa Rus of the Netherlands, but US Open quarter-finalist Tsvetana Pironkova of Bulgaria lost 7-5 6-2 to Taiwanese Hsieh Su-wei.

Hseih will next play Canada's Bianca Andreescu, who beat Mihaela Buzarnescu 6-2 4-6 6-3 in her first match for 15 months.

Second seed Simona Halep raced into the second round with a 6-2 6-1 win over Australian wildcard Lizette Cabrera in just 59 minutes.

Czech Petra Kvitova, who was runner-up to Osaka in 2019, also advanced by beating Greet Minnen of Belgium 6-3 6-4.

Seventh seed Aryna Sabalenka of Belarus was also victorious on the first day, beating Slovakia's Viktoria Kuzmova 6-0 6-4.

Serena channels Flo-Jo in rapid win

Williams made a nervy start against Siegemund, double-faulting on the first point of the match before losing her opening service game.

However the American, who withdrew from last week's Yarra Valley Classic semi-final with a shoulder problem, did not take long to find her footing.

She hit 16 winners and four aces against 51st-ranked Siegemund, setting up a second-round meeting with Serbia's Nina Stojanovic.

Williams wore a one-legged, black, pink and red catsuit, which she later said was a tribute to late American track and field icon Florence Griffith-Joyner.

"I was inspired by Flo-Jo, who was a wonderful track athlete, amazing athlete when I was growing up," Williams said.

"Watching her fashion, just always changing, her outfits were always amazing."

Williams is joined in the second round by Osaka and her 40-year-old sister Venus, who beat Belgium's Kirsten Flipkens 7-5 6-2.

Osaka will play France's Caroline Garcia next, while the elder Williams sister faces veteran Sara Errani.

Italy's Errani beat 30th seed Wang Qiang, who stunned Williams in the third round last year, 2-6 6-4 6-4.

Emotional Andreescu relishes return

Andreescu was playing her first match in 467 days after picking up a knee injury shortly after winning her maiden Grand Slam at the US Open.

Unable to play in 2020 because of the injury and the coronavirus pandemic, the 20-year-old withdrew from the warm-up tournament last week to guard against any issues.

She was impressive against Romania's Buzarnescu, finding her range with her forehand and digging in at the key moments, staving off three break points at 3-3 in the decider before securing the key break.

"Last night I did cry, and I'm not afraid to say that because everyone cries sometimes," said Andreescu, who teared up after the winning point.

"But it's a good release for me because in my head, all I was thinking about were the last 15 months and how tough they were, and they were tough for many reasons."

'No complaints' over electronic line calling

There are no line judges at the Australian Open this year in an attempt to keep the tournament bio-secure and the move has been welcomed by players so far.

Instead, ball-tracking cameras are used. Voices call out decisions in real-time, with recordings made by Australia's health workers, firefighters and other emergency services personnel as a tribute to their work.

"I feel like if they do want to continue this way, I actually have no complaints about it because I think that there's a lot of arguments that aren't going to happen because of this technology," said Osaka.

Serena Williams added she thought it was "for the best".

"It's interesting, It's definitely different," the American said. "I'm loving it here, so I just needed to adapt, and now I'm adapted to it. I think it's for the best.

"I think it's not too much that can be wrong - there can be some close calls that you can check, but I think it's good."