Defending champions Novak Djokovic and Aryna Sabalenka entertained bumper crowds with contrasting first-round victories over teenagers as the Australian Open got underway a day earlier than usual on Sunday.

Djokovic, who admitted he had been feeling under the weather for the last few days, needed more than four hours on Rod Laver Arena to subdue qualifier Dino Prizmic 6-2, 6-7 (7-5), 6-3, 6-4 and remain on course for an 11th title at Melbourne Park.

That kept Sabalenka waiting almost until midnight to open her title defence against Ella Seidel but the second seed did everyone a favour by making light work of the German qualifier with a quickfire 6-0, 6-1 victory.

Former champion Caroline Wozniacki advanced to the second round after four years away from Melbourne Park when Magda Linette retired due to injury while trailing 6-2, 2-0.

Djokovic’s contest was the longest first-round match he had ever played at a major and he lavished praise on grand slam debutant Prizmic for taking the game to him. “I mean, I had an amazing opponent tonight,” he said of the Croatian.

“For an 18-year-old... I was impressed with his mentality, with his approach, with his game.”

Sabalenka was clearly delighted to be back at the site of her first grand slam triumph. “I’m super happy to be back. The last time I was here I had incredible memories, unforgettable memories,” the 26-year-old told the fans who stuck around to watch her ruthless 53-minute walloping of Seidel. “Hopefully, I can stay until the very, very, very last day.”

In the first match of the day on the main showcourt, fourth seed Jannik Sinner eased past Botic van de Zandschulp 6-4, 7-5, 6-3 in his first match of the new year.

Fifth seed Andrey Rublev had a much tougher time getting into round two, pushed all the way by debutant Thiago Seyboth Wild in his 7-5, 6-4, 3-6, 4-6, 7-6 (8-6) win.

Rublev was clearly furious at his inability to see off the world No. 78, who produced some sensational shots to frustrate the Russian and earn the support of the Margaret Court Arena crowd.

“I’m not going to forget this match,” said the relieved Rublev, who said he had flashbacks of the Brazilian’s upset of his compatriot Daniil Medvedev in the first round of last year’s French Open.

Taylor Fritz also needed five sets to beat South American opposition, the 12th seed prevailing 4-6, 6-3, 3-6, 6-2, 6-4 over Argentine Facundo Diaz Acosta in another four-hour marathon.

The addition of an extra day to the tournament to help clear the first-round matches left the early schedule a little light on star power.

Czech Barbora Krejcikova was the only former women’s grand slam winner playing in the day session and the ninth seed had to come from behind to beat Japanese wildcard Mai Hontama 2-6, 6-4, 6-3.