Nadal in the pink as Sharapova hits all-time low at Australian Open

Top seed Rafael Nadal turned on the style as he launched his bid for a record-equalling 20th Major title at the Australian Open on Tuesday, but falling star Maria Sharapova hit a career low.

Australia's Nick Kyrgios also cantered into the second round, but fourth seed Daniil Medvedev had to fight his way past American Frances Tiafoe in four sets.

Nadal, one shy of Roger Federer's Grand Slam mark, dropped only five games as he swatted aside Bolivia's Hugo Dellien 6-2, 6-3, 6-0 in just over two hours at a sunny Rod Laver Arena.

"It was a positive start," said the reigning Roland Garros and US Open champion, wearing a bright pink singlet and matching trainers.

"What you want in the first round is just to win, and it's better if it's in straight sets."

He joins Federer and defending champion Novak Djokovic in round two as the Big Three look to tighten a stranglehold that has brought them all but one of the last 14 Australian Open titles.

Nadal, the first player to be world number one in three different decades, is still thriving at 33 but it's a different story for five-time Grand Slam winner Sharapova.

The 32-year-old, playing on a wildcard as she wrestles with a shoulder injury, lost 6-3, 6-4 to Croatian 19th seed Donna Vekic, making her an opening-round loser at three straight Grand Slams for the first time.

The future looks uncertain for the former world number one, who won Wimbledon when she was just 17 but has not reached a Grand Slam final since she lifted the 2014 French Open trophy.

"I can speak about my struggles and the things that I've gone through with my shoulder, but it's not really in my character to," Sharapova said.

"I was there, I put myself out there (playing). As tough as it was, I finished the match - it wasn't the way that I wanted."

Britain's Johanna Konta, a two-time Slam semi-finalist, also fell at the first hurdle as she battles to overcome a knee problem, losing 4-6, 2-6 to unseeded Tunisian Ons Jabeur.

Stormy Fognini

On a bumper day of 88 first-round matches, after rain wiped out half of Monday's schedule, former US Open champion Marin Cilic and Milos Raonic both moved safely through.

Italy's Fabio Fognini, two sets down against America's Reilly Opelka when their match was suspended on Monday, returned to win it in five after a stormy encounter when both players argued furiously with the umpire.

A new star emerged in 18-year-old Italian Jannik Sinner, last year's NextGen champion, who earned his first Grand Slam victory against Australia's Max Purcell.

Australia's Kyrgios, who has spearheaded fundraising efforts for the country's deadly bushfire disaster, kept his notorious temper in check despite being taken to two tie-breaks in a 6-2, 7-6 (7/3), 7-6 (7-1) win over Lorenzo Sonego of Italy.

"I feel super-comfortable, you guys are the best. I feel the support.... I am ready to go again," Kyrgios told the crowd.

Medvedev, the narrow loser to Nadal in September's US Open final, dropped the second set against Tiafoe before recovering to win 6-3, 4-6, 6-3, 6-2. Austria's Dominic Thiem, who has reached the last two French Open finals, went through in straight sets against Adrian Mannarino, while 2014 champion Stan Wawrinka needed four to get past Damir Dzumhur.

Seventh seed Alexander Zverev beat Marco Cecchinato in straight sets but there was disappointment for France's Jo-Wilfried Tsonga, the 2008 finalist, who retired with a back injury against Australia's Alexei Popyrin.

Elsewhere, women's fourth seed Simona Halep survived some painful-looking falls to beat America's Jennifer Brady, and 2016 champion Angelique Kerber dropped only four games against Elisabetta Cocciaretto of Italy. Air pollution from the bushfires disrupted the build-up to the year's first Grand Slam, but after Monday's heavy rain the skies were clear and sunny on Tuesday.