Rafael Nadal's injured back didn't slow his bid for a record 21st Grand Slam title on Tuesday, as women's world number one Ashleigh Barty romped to a 6-0, 6-0 'double bagel' at the Australian Open.
On a day when women's champion Sofia Kenin also reached round two, but two-time winner Victoria Azarenka lost after breathing problems, Nadal and Barty were the headline acts at the coronavirus-delayed Slam.
Spanish great Nadal, who pulled out of last week's ATP Cup with back problems, beat Serbia's Laslo Djere 6-3, 6-4, 6-1 in one hour and 52 minutes on a sun-kissed Rod Laver Arena.
"It's been a tough 15 days for me," said the 2009 champion, whose back stiffness first flared during an exhibition match last month.
"I needed to survive today and that's what I did. I'm happy to be through and I think I did a good job today. Straight sets is what I needed."
Nadal, 34, is attempting to outstrip his old rival Roger Federer, who is out with injury, and take sole ownership of the all-time record for Grand Slam titles.
After world number one Novak Djokovic eased through late on Monday, Russia's Daniil Medvedev extended his winning streak to 15 matches with an emphatic 6-2, 6-2, 6-4 victory over Canada's Vasek Pospisil.
The 2019 US Open finalist is raising hopes of a maiden Grand Slam title with his unbeaten run, which includes winning the Paris Masters, ATP Finals and last week's ATP Cup with Russia.
Russian seventh seed Andrey Rublev also continued his winning start to the year with a straight-sets victory over German Yannick Hanfmann 6-3, 6-3, 6-4.
And Greek fifth seed Stefanos Tsitsipas made short work of French veteran Gilles Simon, winning 6-1, 6-2, 6-1 in 92 minutes.
"I think I played a spectacular match from the beginning to the end," said the confident 22-year-old.
- Barty started -
Barty also outclassed Montenegro's Danka Kovinic, losing only 10 points as she raced into round two in just 44 minutes.
With the win Barty, last year's semi-finalist who sat out most of the 2020 season, ramped up hopes of a first Australian women's winner in 43 years.
"It felt great to be here," she said. "I tried to stick to my process and routine but I just wanted to have fun."
Women's champion Kenin was less convincing and she audibly vented her frustrations during her 7-5, 6-4 win against Australian Maddison Inglis, who is ranked outside the top 100.
Two-time major-winner Garbine Muguruza, who was stunned by Kenin in last year's final, had little trouble beating Russia's Margarita Gasparyan 6-4, 6-0.
But there were distressing scenes as an ailing Azarenka, the 2012 and 2013 champion, went out to Jessica Pegula.
Azarenka, who was one of the players locked down in hard quarantine pre-tournament and not allowed out of her room for 14 days, began to suffer in the second set.
The 2020 US Open runner-up, who only played one warm-up match last week, was seen gasping and using an inhaler, and then looked close to collapse on court. After a medical timeout she played on but lost 7-5, 6-4.
America's Tennys Sandgren and Spain's Paula Badosa, who were also in hard quarantine, both went out but there was an impressive, straight-sets win for Spanish Grand Slam debutant Carlos Alcaraz, 17.
"He has all the ingredients to become a great champion," Nadal said of Alcaraz, who swept past Botic Van de Zandschulp 6-1, 6-4, 6-4.
Elsewhere, fifth seed Elina Svitolina of the Ukraine was pushed hard by Czech Marie Bouzkouva before coming through 6-3, 7-5 (7/5).
She will next play 16-year-old American Coco Gauff, who beat Venus Williams and Naomi Osaka last year and enjoyed a straightforward 6-3, 6-2 win over Switzerland's Jil Teichmann on Tuesday.
The year's first Grand Slam has started three weeks late because of coronavirus problems, with players and officials required to quarantine for two weeks after arriving in Australia.
Crowds are limited, masks are mandatory and movement is curbed around Melbourne Park, where Monday's attendance was 17,922, compared with 64,387 on day one in 2020.