Some very early signs of frustration from Aryna Sabalenka as she pelts the ball into the net.

But she pulls us back to deuce with some massive forehands that Camila Osorio can't cope with.

Nice from Camila Osorio as she sinks a lovely cross-court backhand winner, recovering from an earlier double fault.

Ah. But there's a second double fault to drag Sabalenka to 40-30.

And then a huge return from the top seed on Osorio's second serve. Deuce.

Two more break points saved by Harriet Dart, who was down 15-40 before coming through a second deuce with an ace and a wide serve returned into the net to hold.

Peyton Stearns holds to 30 to keep the first set on serve.

Image source, Getty Images

Aryna Sabalenka is just about to get her title defence bid under way.

Things haven't gone to plan for the top seed lately and her position as world number one is under serious threat.

With 2,000 points to defend at Flushing Meadows and Kazakhstan's Elena Rybakina now trailing by only 434, Sabalenka must win again to extend her 99-week run as the world number one.

A first-round defeat today would be far from ideal for the two-time defending champion.

Camila Osorio will serve first to get us up and running...

*denotes next server

Marion Bartoli
Former Wimbledon champion on Sky Sports

I was so sad. It was so sad to watch. To see Novak Djokovic suffering that much was breaking my heart.

The way he was physically and health-wise struggling is what worries me the most. Health should come first and surely it should come first for Novak.

You can see how much he is torn with the decision whether he should keep on playing, whether he should retire.

Image source, Getty Images

The defeat ended Novak Djokovic's latest bid for a standalone record 25th Grand Slam singles title, which would move him clear of Australia's Margaret Court.

Afterwards Djokovic revealed he had been hampered by a "health condition" which has been "bothering" him in oppressive conditions over a number of years and, discussing the issue with reporters shortly after losing to Navone, called it a "serious issue".

"It's something that I have been carrying pretty much every match this year - vomiting, throwing up," Djokovic said.

"And then my whole body starts to collapse basically, cramping and pain - the back just gave up in the end and shoulder, and I couldn't close it out."

The first set on court 12 is going with serve.

Harriet Dart had four opportunities to break in the opening game against Peyton Stearns but couldn't capitalise.

The Briton has since saved a break point in her second service game before Stearns eased through a hold to love.

Before we dive into any of today's action, let's recap on what happened on Arthur Ashe Stadium overnight in the UK.

Novak Djokovic, the 24-time Grand Slam champion, broke down in tears during a shock first-round defeat by Argentina's Mariano Navone.

The 39-year-old was overcome by emotion in the deciding set of a dramatic match where he struggled physically throughout and had to vomit into a towel bin.

It was the first time the Serb had been beaten in the opening round at Flushing Meadows and the first time he had lost in the opening round of a Grand Slam tournament since 2006.

Three Brits are in action on day two.

Qualifier Harriet Dart is under way on court 12 against American Peyton Stearns.

That match will be followed by the resumption of Jacob Fearnley's first-round meeting with Spaniard Martin Landaluce. Play was suspended with Landaluce leading 4-3 and 40-0 in the first set.

Harry Wendelken, who came through qualifying to reach his second Slam of the year, is third on court five for his US Open debut. He faces Italian 21st seed Luciano Darderi.

Toby Samuel and Katie Boulter have already booked their spots in round two, beating Tomas Machac and Carol Young Suh Lee, respectively, but Cameron Norrie lost to Luca Van Assche in four sets.

Here's how the day session is looking on the main show courts...

Arthur Ashe Stadium

• Aryna Sabalenka [1] v Camila Osorio
• Roman Safiullin v Carlos Alcaraz [2]

Louis Armstrong Stadium

• Stefanos Tsitsipas v Arthur Fils [10]
• Ashlyn Krueger v Amanda Anisimova [10]

BBC Radio 5 Sports Extra

We've got live radio commentary from Flushing Meadows all the way until midnight UK time.

Just head to BBC Radio 5 Sports Extra on BBC Sounds or click the 'listen live' button at the top of this page to tune in (UK only).

And welcome along to day two of the 2026 US Open!

Play is already under way in New York and we've got plenty to look forward to this afternoon and evening - including the return of Carlos Alcaraz.

There's also a few Brits in action later on, while Stan Wawrinka will be hoping to make the second round in his final-ever appearance at a Grand Slam.

But we'll start on Arthur Ashe, where world number Aryna Sabalenka is just about to start her title defence bid against Colombia's Camila Osorio.

Image source, Getty Images