MELBOURNE, Australia (AFP) — Madison Keys admitted she was “very nervous” as she launched her title defense with an unconvincing win on Tuesday at the Australian Open, where Jannik Sinner later begins his bid for a Melbourne hat-trick.

Two-time former champion Naomi Osaka is also in action on day three of the first Grand Slam of the year, as is highly promising Brazilian teenager Joao Fonseca.

A jittery Keys lost the first four games before rallying to beat Ukraine’s Oleksandra Oliynykova 7-6 (8/6), 6-1 on Rod Laver Arena.

“I’ve been thinking about this moment for basically a year,” the American ninth seed said of walking out on center court again.

“I’m so happy to be back in Melbourne. Obviously, I was very nervous at the start.”

Keys stunned Aryna Sabalenka 12 months ago in a three-set epic to win her first major crown at the age of 29, but she failed to push on from there in 2025, winning no more titles.

She started her season with quarter-final exits at Brisbane and Adelaide, admitting before the Grand Slam to being nervous as defending champion.

And so, it proved as she threatened to implode against the Ukrainian ranked 92 in the world, before finding her feet to pull away with ease in the second set.

Also in the women’s draw, Janice Tjen clocked another milestone in her rapid rise as she became the first Indonesian to win a match at the Australian Open in 28 years.

Unseeded Tjen stunned Canadian 22nd seed Leylah Fernandez 6-2, 7-6 (7/1) to surge into the second round and add to her growing list of scalps.

Tjen, who this time last year was ranked 413 but is now the world number 59, is the first Indonesian to win a match at the major since Yayuk Basuki in 1998.

Former world number one Osaka, the 16th seed, featured in the final encounter of the day on center court, against Croatia’s Antonia Ruzic.

The 28-year-old Japanese has struggled to get back to the form and fitness that took her to the Australian Open title in 2019 and 2021.

Top-10 seeds Elena Rybakina and Belinda Bencic also begin their campaigns.

Sinner will hope to have a far smoother start to his title defense than Keys.

The Italian was a comfortable winner over Alexander Zverev in last year’s final and if he wins the tournament again would join Novak Djokovic as the only men in the Open era to win three successive Melbourne crowns.

The second seed faces French world No. 93 Hugo Gaston.

The chief threat to his Australian Open dominance is top-ranked Carlos Alcaraz, who is bidding to win the tournament for the first time and seal a career Grand Slam of all four majors at just 22.

The Spaniard eased through his opening match on Sunday in straight sets.

Following defeat to great rival Alcaraz in the US Open final, the 24-year-old Sinner vowed to add more variation to his game.

“We worked a lot on trying to make the transition to the net. The serve we changed a couple of things,” he said.

“When you are at the top level, these are the small details that make the difference.”

Also playing Tuesday in the first round are Italian fifth seed Lorenzo Musetti, all-action eighth seed Ben Shelton, and his fellow American and ninth seed Taylor Fritz.

There will be interest in the 19-year-old Fonseca, who was tipped on the eve of the tournament by Roger Federer to one day challenge the duopoly of Alcaraz and Sinner.

The 28th seed plays another American in Eliot Spizzirri.