Nadal has only lost twice in the first round at Grand Slams - to Steve Darcis at 2013 Wimbledon, and to Fernando Verdasco at Melbourne Park in 2016.
The former world number one was far from ideal, committing three double faults and eight unforced errors. NextGen Finals champion Stefanos Tsitsipas also went through in four sets. Vekic lost 6-4, 4-6, 6-1 to Kimberly Birrell, a 20-year-old Australian ranked 240th who got into the field as a wild card.
Wozniacki, who is battling rheumatoid arthritis, sealed the match with a forehand victor on her third matchpoint and will next meet Sweden's Johanna Larsson, who progressed after Vera Lapko of Belarus retired while trailing 7-6 (5), 3-0. It was an emotional win for the Dane who is struggling with rheumatoid arthritis and she was in tears afterwards.
The second-seeded Spaniard had pulled out of the Brisbane warm-up with a thigh strain to raise doubts about his campaign but he allayed those fears on Rod Laver Arena against an error-prone opponent.
Many netizens hailed Sharapova's play in the first round of the Australia Open as solid.
She said: "Obviously the shoulder hasn't been much of a secret in the past year".
Virat Kohli on Pandya || Rahul row: Don't support inappropriate comments
Supriyo also said there should be a "thick" line between "reprimanding" the players and "destroying" them. Pandya posted an apology to his social media accounts claiming he had "reflected" on his comments.
"I'm still working through some painful days. I don't know my percentage, but was a lot of good positions after the first serve", he said.
Eleventh seed Aryna Sabalenka from Belarus also safely negotiated round one on a day when temperatures were soaring towards a forecast 37 Celsius (98.6 Fahrenheit).
He was joined in the third round by another kid from the US who'd never been that far at Melbourne Park, 21-year-old Taylor Fritz, who saved 12 of the 13 break points he faced while dispatching No. 30 seed Gael Monfils of France 6-3, 6-7 (8), 7-6 (6), 7-6 (5).
The centre court humiliation had Dart weeping as she beat a hasty exit and Sharapova had little sympathy for the 22-year-old after her nightmare debut at Melbourne Park.
In women's singles play and men's and women's doubles and mixed doubles, the deciding set of three sets will be played with a 10-point tiebreaker at 6-6.
It seemed Boulter wasn't told, fist-pumping and walking to the net at 7/4 before being reminded of the new rule.
The Briton prevailed 6-0 4-6 7-6 (10-6) as she sent the former semi-finalist packing, Boulter recording the biggest win of her career to date.