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Stefanos Tsitsipas beats Andy Murray 6-2 6-7 (7-9) 6-3 3-6 6-4 on Arthur Ashe in first round
British number one Dan Evans beats Brazil's Thiago Monteiro 6-3 6-7 (6-8) 6-4 6-1
Britain's Heather Watson and Harriet Dart make first-round exits
British number one Johanna Konta pulls out of tournament hours before her scheduled first-round match
Later: Cameron Norrie v Spain's Carlos Alcaraz
Naomi Cavaday
BBC Sport tennis commentator
You could not have asked for a better start from Murray. He looks so sharp.
I think he just knows he has to lift his level and he is doing it in every area.
*Murray 4-1 Tsitsipas
Andy Murray is quick to the net to set up another break point - and Tsitsipas gets a volley all wrong to fall a double break down in the first set!
A dream start for Murray, he's playing some excellent tennis.
Russell Fuller
Tennis commentator on BBC Radio 5 Live
I am hearing now that a left thigh problem is the reason Johanna Konta is out of the US Open.
Murray 3-1 Tsitsipas*
Murray is moving really well so far and is quickly back to the baseline to get to a Tsitsipas lob.
He clips the net however as the Greek moves 30-0 up on serve, but battles back with an emphatic cross-court forehand winner for 30-30. Great stuff!
Garcia 6-7 (6-8) Dart
In further good news for British fans, Harriet Dart has just taken the first set against France's Caroline Garcia.
The 25-year-old world number 151 won the tie-break 8-6 against Garcia, who is ranked 89 places above Dart.
Heather Watson is also in action. Her match against Slovenia's Kaja Juvan is on serve in the first set currently.
Murray 3-1 Tsitsipas*
A cracking ace takes Murray to 40-0.
That's followed up by a double fault, but Tsitsipas misses with a backhand and it's 3-1 to the Briton in the opening set.
*Murray 2-1 Tsitsipas
Now, can Andy Murray build on that early breakthrough?
Stefanos Tsitsipas is making a fair few errors in the opening exchanges and another gets Murray up and running.
*Murray 2-1 Tsitsipas
Stefanos Tsitsipas recovers well to save the first two break points, but he can't survive another!
A huge fist pump from Andy Murray as his opponent makes another error under pressure.
A superb start by the former world number one.
Naomi Cavaday
BBC Sport tennis commentator
It is a bit of a nervy start for Tsitsipas. Maybe the aura of Andy Murray is getting him a bit.
Image source, Getty ImagesMurray 1-1 Tsitsipas*
Oh hello...
Another early chance for Murray on the Tsitsipas serve at 0-30.
And the Greek frames a return well wide to hand over three break points!
#bbctennis
Ben Wire: Murray will know exactly what he wants out of this tournament; he'll have few expectations beyond performance and stamina. I think he'll be hoping to get into the top 20 by end of the season to have a real chance in 2022/2023.
Murray 1-1 Tsitsipas*
A solid start from Andy Murray on serve.
Three winners takes the 2012 champion to 40-0, and he forces Tsitsipas long to seal a hold to 15.
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*Murray 0-1 Tsitsipas
Some good early pressure from Andy Murray in Stefanos Tsitsipas' opening service game there, but the Greek is able to hold.
Naomi Cavaday
BBC Sport tennis commentator
One of the biggest strengths for Tsitsipas is his serve.
We know Murray is one of the best returners out there but the return is tough when you haven't played enough matches - you have to be so sharp.
Murray 0-0 Tsitsipas*
Tsitsipas gets to 30-0 before Andy Murray can get on the board, but the Greek drops a forehand into the net and it's 30-30...
Deuce! A wayward forehand from the baseline by Tsitsipas hands Murray an early opportunity.
#bbctennis
As always, it'd be great to get your thoughts and feelings on things as we prepare ourselves for another potential Andy Murray rollercoaster.
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Murray 0-0 Tsitsipas*
Stefanos Tsitsipas gets us under way on Arthur Ashe!
Murray v Tsitsipas
Speaking before the US Open, three-time Grand Slam winner Murray said he has found his lack of consistency in recent months frustrating.
"My level is up and down with no real consistency. There are moments in matches where I play well and then I make mistakes or miss returns. I wish I wasn't doing that," Murray said.
"My level is around 50 or 60 in the world. It's frustrating because if I wasn't moving great and not feeling good physically then I would be a bit easier on myself.
"But when I'm winning a low percentage of second-serve points, that's got nothing to do with the physical side of things."
Image source, Getty ImagesMurray v Tsitsipas
Image source, Getty ImagesStefanos Tsitsipas reached his maiden Grand Slam final at the French Open earlier this year, but exited in the first round at Wimbledon.
In the build-up to the US Open, the Greek third seed has reached semi-finals at the Canadian Open and Cincinnati Masters.
On facing Murray, he said: “He's someone that has been putting a lot of work to get back. He's been playing very good tennis to be standing where he's at right now.
"I'm going to go for it and try my chances against him. He's someone that won't give up. I'll have to bring some good tennis from my side.”