Ukraine had a banner start to Monday at the Australian Open. Dayana Yastremska delivered the biggest upset of the tournament so far, thumping No.7 seed Marketa Vondrousova, while Elina Svitolina cruised through to the second round at the expense of Australian wildcard Taylah Preston.

Former World No.21 Yastremska, a qualifier in Melbourne this year, toppled the reigning Wimbledon champion Vondrousova in under an hour, 6-1, 6-2, to record the first Top 10 upset of the tournament.

Svitolina, meanwhile, was the day's first winner, as she ripped off six straight games from 2-1 down in the opening set against the 18-year-old World No.203 en route to a 6-2, 6-2 triumph.

"I'm happy to be back. Happy winning the first round again here," Svitolina said afterwards. "I'm just happy with the way I started the Australian Open in general. Of course not easy at the beginning of the match, but then played quite solid, so I'm happy with the win today."

Inside the upset: The win against Vondrousova is Yastremska's fourth in her career against a Top 10 player, and first at a Grand Slam. it's also her second against Vondrousova, but the last win came six years ago. 

Yastremska's last win against a Top 10 player came against then-World No.3 Barbora Krejcikova in Dubai two years ago. 

The now-World No.96 was as dominant on the stat sheet as she was on the scoreboard. The 23-year-old hit 26 winners to Vondrousova's five, and broke serve five times as the Czech served up seven double faults. 

The match was at its most competitive in the first two, and the last two, games. Yastremska won two multi-deuce games to start the match -- and broke Vondrousova after four break points for 2-0. Four games went to deuce in the second set, and after failing to convert a match point in the seventh game, Yastremska saved a break point in the subsequent one before closing things out on her third opportunity.

Yastremska speaks: "Last time I played with Marketa, I lost to her. It was a tough match," Yastremska said afterwards. "Today, in the morning, I was a little bit nervous. I think I had a good focus and I just tried to show my best. 

"I know I can play much better, but still I think it was a good game. I really enjoyed to be there."

Siegemund upsets Alexandrova, maintains unbeaten start to 2024

United Cup heroine and Adelaide quarterfinalist Laura Siegemund continued her strong start to the year, coming from 4-2 down in the third set to upset No.17 seed Ekaterina Alexandrova 6-2, 3-6, 7-6[9] in 3 hours and 1 minute.

No.78-ranked Siegemund is unbeaten in both singles and doubles this season so far (having withdrawn from Adelaide ahead of her quarterfinal due to a left leg injury). This result was her second Top 20 win of 2024, and first win over Alexandrova in three meetings. Siegemund, the reigning WTA Finals doubles champion, will next play doubles World No.1 Storm Hunter for the first time in singles.

Anastasia Pavlyuchenkova also knocked off a seeded player, moving through to the second round at the expense of 2023 Melbourne quarterfinalist and No.21 seed Donna Vekic, 6-4, 6-4. Pavlyuchenkova, a three-time quarterfinalist at the Australian Open, had lost in the first round twice in her last three visits to the tournament, but broke Vekic twice in each set to move through to a second-round affair with former World No.2 Paula Badosa.

Two other seeds moved on to Round 2, though. No.25 Elise Mertens advanced when Mayar Sherif retired trailing 6-2, 2-0; the Belgian, a finalist in Hobart last week, has now won 11 of her last 13 matches. No.26 Jasmine Paolini was also victorious, defeating Diana Shnaider 6-3, 6-4.

Golubic ousts Kudermetova in three sets; Haddad Maia advances

World No.85 Viktorija Golubic was at her creative best in defeating No.15 seed Veronika Kudermetova 7-6(4), 1-6, 6-1 in 2 hours and 21 minutes. In the pair's only previous meeting, the Swiss player had also meted out a three-set first-round Slam upset, winning 3-6, 6-1, 11-9 at Wimbledon 2021 before going on to her first major quarterfinal.

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Golubic came through another rollercoaster to notch her 10th career Top 20 win, stealing the first set from 4-2 down and winning 20 of the last 27 points of the match. The 31-year-old's variety was on song; she sealed the first set with a backhand lob at full stretch into the opposite corner, and converted match point by dragging Kudermetova from side to side with knifing slices off both wings, before nailing a flat forehand winner.

However, No.10 seed Beatriz Haddad Maia avoided the upset, holding off 18-year-old Linda Fruhvirtova 6-2, 3-6, 6-2 in 2 hours and 18 minutes. The Brazilian found herself embroiled in several gruelling exchanges with the 18-year-old, but raised her game in the third set to ease to the finishing line. Haddad Maia claimed the first break of the decider with a fine backhand down the line winner followed by a drop shot to lead 4-2, then converted her first match point with a fizzing forehand return winner.

Haddad Maia will next play another teenager, 16-year-old junior No.1 Alina Korneeva.