Yes, sportswear as high fashion is having a (long) moment – bike shorts with heels, tracksuits for Paris Fashion Week front rows, too-small pool scuffs with socks. But still, it’s rare for athletes to be better dressed at a sporting event than the celebrities watching them play.

The US Open, which kicked off in New York on August 27, has so far proved the exception.

It started on a style high note with Serena Williams’ entrance into Arthur Ashe Stadium in a black one-shouldered tutu designed by Louis Vuitton’s Virgil Abloh.

Her warm-up jacket was black leather. Her sneakers were sparkly metallic. Her vibe was awesome. It was a rock star moment for tennis, when couture meshed with court culture in a seriously fun way.

Days later, Williams was back. Same tutu dress, but in lilac, which used to be reserved for puffy-sleeved bridesmaid dresses but this year – in a deeper shade – is Pantone’s hottest colour of 2018.

The former world No.1 wasn’t alone in knocking it out of the park while knocking it out of the park. Andy Murray’s electric neon balayage T-shirt was techno cool, and Rafael Nadal – thank you, higher power – has put his knickerbocker days behind him.

In New York, he was back to great basics: shorts, singlet, guns.

Italy’s Camila Giorgi rocked a contemporary retro look: white, halter neck, tiny flippy skirt with pale floral details.

Maria Sharapova went to the dark side, in a black dress with asymmetrical white and grey deep side panels.

Australia’s Ash Barty had a French vibe in powerhouse crisp red, navy and white and charm necklace.

Given it was the golden anniversary of the US Open, a stellar array of celebrities turned out for opening night. New York’s own Maxwell performed, Gladys Knight rocked up and Hugh Jackman and wife Deborra-Lee Furness cosied up in the stands.

So far, so good. Or so mediocre, as it turned out. If there was a style practice court, most celebs would need to spend more time there, bashing some concepts around.

Singer Kelly Clarkson, who changed her outfit to a fringed silver one to headline on stage, showed up in summer heat in a Jetsons-style mini with tights, stiletto ankle boots and goth manicure. Wrong note, lady.

Vera Wang, who spends her life designing bridal dresses, is maybe sick of white and was giving a cry for intervention help by showing up as Angelina Jolie when she’s visiting Cambodia. Quite cool but also weird.

Wendi Deng Murdoch looked less like the cashed-up ex-wife of a media mogul, more like she had read the dress code as ‘adorable’ and decided a CWA apron and kitsch pop of colour purse would fit the bill.

Anna Wintour sat next to Ms Deng Murdoch in the stands, and showed her things on her phone. The US Vogue editor-in-chief, a massive Roger Federer fan, showcased her own tennis arms in a paisley silk tea dress and statement necklace.

US ambassador to the United Nations Nikki Haley took time out from being powerful to whip up a cheerful gored frock on her Janome and pair it with daggy wedges – negotiate some flats next time, please.

Did Hugh Jackman learn nothing from the English men at Wimbledon? Or Oceans 11? Jacket, Mr Jackman, for the greatest showman.

At the opposite end of the spectrum, former heavyweight champ Mike Tyson was respectful but possibly overdressed – the formal black shoe is hard to pull off at the tennis – or had made his way straight to the Open from a suburban wedding where he was one of eight groomsmen.

Singer Gladys Knight was a total boss, thanks to the great sneakers and breezy street style.