MELBOURNE, Australia >> After wasting a set point in the second tiebreaker with an ill-conceived drop shot, Jannik Sinner quickly reverted to what’s been working for him and finished off a straight-set win over Nicolas Jarry to begin his Australian Open title defense.

The 7-6 (2), 7-6 (5), 6-1 victory on Rod Laver Arena extended Sinner’s winning streaks to 15 on both the tour and on hard courts in Grand Slams.

After all the pre-tournament attention on the 2024 doping cases of Sinner and long-time women’s No. 1 Iga Swiatek, both started the year’s first Grand Slam tournament about the same time on nearby courts on Day 2.

Top-ranked Sinner had to grind for two long, tiebreak sets against No. 35-ranked Jarry, a 29-year-old from Chile, before finding his touch.

“It was a very close one because the first sets, they can go both ways,” Sinner said. “In the third set when I broke it the first time, that gave me a little bit of room to breathe.”

Sinner has got a good record at Melbourne Park in that department. He rallied from two sets down in last year’s final to beat Daniil Medvedev for his first Grand Slam title, coming off a semifinal upset of 10-time champion Novak Djokovic.

While Sinner was deep into his match against Jarry, Swiatek, a five-time major winner from Poland, fended off top-ranked doubles player Katerina Siniakova 6-3, 6-4 on John Cain Arena.

Coco Gauff had a little difficulty adjusting to the sun at one end of Rod Laver Arena in Monday’s first marquee match and dropped an early service game before quickly settling into a rhythm in a 6-3, 6-3 win over 2020 champion Sofia Kenin.

Third-seeded Gauff beat Swiatek to win the title at the WTA Finals last November and started this season by helping the U.S. to victory at the United Cup last week, against beating No. 2 Swiatek in the final.

Gauff, the 2023 U.S. Open champion is wearing a Marvel-inspired bodysuit and skirt at Melbourne Park and she’s radiating confidence and calm.

Another 20-year-old American, Alex Michelsen, produced the biggest win of his young career with a 7-5, 6-3, 2-6, 6-4 first-round upset of 2023 Australian runner-up Stefanos Tsitsipas.

Michelsen’s three booming service returns in the ninth game of the fourth set helped him earn a vital break against the 11th-seeded Tsitsipas and, after shaking off jitters on his own serve, he closed out for his first victory over a player ranked in the top 20 at a Grand Slam. No. 17 Frances Tiafoe advanced in five sets over Arthur Rinderknech of France.

Gauff will next play Jodie Burrage of Britain. No. 7 Jessica Pegula also advanced along with No. 12 Diana Shnaider, No. 28 Elina Svitolina, and Belinda Bencic, who ousted No. 16 Jelena Ostapenko. Lucia Bronzetti of Italy advanced over No. 21 Victoria Azarenka, a two-time Australian Open champion.

Briefly

U.S. >> Naomi Osaka said after her first round victory that there was a fire burning three blocks from her L.A. home, and she sent someone to retrieve her daughter’s birth certificate.

Australia >> Nick Kyrgios said after losing 7-6 (3), 6-3, 7-6 (2) to unseeded Jacob Fearnley in the first round Monday night that the contest probably was the last Australian Open singles match of his career.