No.12 seed Simona Halep had been handed one of the toughest openers in the 2021 US Open draw, but skilfully held off Camila Giorgi 6-4, 7-6(3) in one hour and 33 minutes to move into the second round.

Halep, a semifinalist in Flushing Meadows in 2015, was considered to be among the more vulnerable seeds. The Romanian had been sidelined from Roland Garros, Wimbledon and the Olympic Games due to a left calf tear that she sustained in Rome. Two tournaments into her return in Cincinnati, she was forced to withdraw due to a right thigh injury.

By contrast, Giorgi's recent hot streak saw the Italian lift the biggest trophy of her career in Montreal two weeks ago, a title run that saw her display control and patience as well as her famed raw power.

But here, Halep asserted her authority with a dominant serving performance. The 29-year-old faced, and saved, just one break point as she advanced to 6-4, 5-4 lead. Giorgi raised her game with her back to the wall and twice prevented Halep from serving out the win, saving two match points at 5-6, but the former World No.1 held her nerve to ease away with the ensuing tiebreak.

By the numbers: It's not often that Halep can be said to serve her way to victory, but that was certainly the case against Giorgi. She won 83% of her first serve points, including 15 out of 17 in the first set alone, and fired six aces.

Both players found a similar number of winners, with Giorgi's 16 edging Halep's 14, but the unseeded World No.36 also committed 31 unforced errors to Halep's 16. The timing of these was more important than the amount, though. At 4-4 in the first set and 2-2 in the second, Giorgi coughed up error-strewn games that gave up key breaks all too easily.

Turning point avoided: The flurry of winners with which Giorgi broke Halep back for 5-5 and 6-6 in the second set was the level many had been expecting of her from the off. A backhand winner to seal the first of those breaks and a breathtaking, net-skimming forehand winner to save a second match point were the most stunning of her shots.

But by then it was too little, too late. Giorgi had the opportunity to move up 3-1 in the tiebreak, but ballooned a drive volley several metres over the baseline. She conceded the match with three consecutive unforced errors.

In Halep's words: "I served well also the previous tournaments, so I feel a little bit stronger there. I worked a lot in the break when I couldn't actually move that much because of the leg. So I did practice a lot of serves... I'm happy that I can see my serve improving, and I can win some easy points with it. So I have been looking for it many years, but now finally I can feel it stronger."

What's next for Halep: A first encounter with lucky loser Kristina Kucova in the second round. Kucova, 31, reached her maiden WTA final last month in Gdynia; competing in just her second US Open main draw, she scored her first win here 7-5, 6-1 over Ann Li. Halep will be seeking to make the third round for the first time since 2016.

Collins ends Suárez Navarro's US Open career

Surging No.26 seed Danielle Collins booked her place in the second round of her home major for the second time with a ruthlessly efficient 6-2, 6-4 defeat of Carla Suárez Navarro in one hour and eight minutes.

In July and August, Collins put together a 12-match winning streak across two continents and two surfaces to capture her first two WTA titles in Palermo, on clay, and San Jose, on hard courts. The 27-year-old American, who returned in May from surgery for endometriosis, maintained that form here, slamming 41 winners in just 18 games. Collins' serve was particularly formidable: she conceded just seven points behind it all match, five in the first set and two in the second.

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For Suárez Navarro, the result draws the curtain on a stellar US Open career. The Spanish former World No.6 debuted in the main draw at Flushing Meadows in 2008, losing in the first round to Alisa Kleybanova. She went on to reach two quarterfinals, in 2013 and 2018, as well as three further fourth-round runs in 2011, 2016 and 2017.

Suárez Navarro has also scored a major health victory in 2021 - in April, she was declared cancer-free after a battle with Hodgkin's lymphoma. The 32-year-old is ending her career this year on her own terms with a farewell tour that has also taken in Roland Garros, Wimbledon and the Olympic Games, and received a standing ovation from the crowd as she exited Court 5.

Collins wasn't the only big-hitting seed to progress impressively. No.19 Elena Rybakina took one hour and 16 minutes to get past Aliaksandra Sasnovich 6-2, 6-3, while No.32 Ekaterina Alexandrova fired 42 winners in one hour and 26 minutes to overpower former US Open semifinalist Sara Errani 6-3, 6-2.

Rybakina, 22, reached her maiden Grand Slam quarterfinal at Roland Garros and has backed that up with a fourth-round showing at Wimbledon and Olympic Games semifinal run.

Kanepi, Fernandez pull off comeback wins

A victory very much in character: Kaia Kanepi had only won one WTA main draw match since March coming into the US Open, but when a seed hoves into view the Estonian lifts her game. Initially outplayed, Kanepi reversed her match against No.31 seed Yulia Putintseva for a 2-6, 7-6(4), 6-2 upset.

It was World No.70 Kanepi's 18th win over a seed at a Grand Slam, and the eighth of those in the first round. The 36-year-old cleaned up her game magnificently as the contest progressed. After tallying four winners to 17 unforced errors in the first set, she turned those numbers around in a glorious decider to post nine winners to only four unforced errors.

Putintseva, a quarterfinalist here last year, seemed to have held off the comeback when she forced a second-set tiebreak after saving two set points at 4-5. But Kanepi's power, even in the extended rallies in which Putintseva thrives, proved too strong.

Kanepi will face Leylah Fernandez, 18, in the second round, with defending champion and No.3 seed Naomi Osaka potentially lying in wait in the third. Fernandez emerged on top of one of the most intriguing first-round clashes, beating qualifier Ana Konjuh 7-6(3), 6-2. The Canadian came from 3-5 down in the first set, saving two set points at 4-5, but seized control of the ensuing tiebreak with a pair of smoothly struck winners and never looked back.

Leylah Fernandez in the first round of the 2021 US Open.

Photo by Mike Lawrence/USTA

More to come...