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.
Hsieh will next play Canada's Bianca Andreescu, who beat Mihaela Buzarnescu 6-2 4-6 6-3 in her first match for 15 months.
The 2019 US Open champion had not played for 467 days after struggling with a knee injury.
"I've been through quite a bit in those 15 months. It wasn't easy," she said.
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.
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.
