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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
David Law
Commentator on BBC Radio 5 Live Sports Extra
It's hard to believe this is happening. Andy Murray is ranked outside the world's top 100. He has barely been able to string together two matches.
Murray 6-2 6-6 Tsitsipas
Murray takes a tumble as he tries to change direction, allowing Tsitsipas to place into an open court for 5-4.
Murray to serve, and a miss by Tsitsipas sets up two set points.
David Law
Commentator on BBC Radio 5 Live Sports Extra
Murray is rushing him, rattling him, unsettling him.
Laura Robson
Former British number one on BBC Radio 5 Live Sports Extra
You don't often see Arthur Ashe this busy for a day match.
This is the match of the day for most people.
Murray 6-2 6-6 Tsitsipas
Tsitsipas finds the net and it's a case of job done for Murray who moves back in front with his two serves.
Oh that is brilliant. A looping lob from behind the baseline beats Tsitsipas and it's a mini-break for Murray at 5-3!
Murray 6-2 6-6 Tsitsipas
Tsitsipas wins consecutive points on serve by forcing Murray into a couple of errors to edge 3-2 ahead. The pressure is back on the Briton, but Murray executes a backhand volley to level things at 3-3.
Murray 6-2 6-6 Tsitsipas*
Both players take the first point on their opponents' first serve of the tie-break, before a timely ace from Murray makes it 2-1.
Murray 6-2 6-6 Tsitsipas*
Tsitsipas misses and we go to a second set tie-break!
*Murray 6-2 5-6 Tsitsipas
Wonderful serving from Andy Murray. Another well placed first serve takes him to 40-15.
Tsitsipas strikes back though. A superb cross-court forehand winner brings him back into contention.
*Murray 6-2 5-6 Tsitsipas
So, the pressure is back on Andy Murray's serve at the end of the second set. Will it be a tie-break, or can Tsitsipas level things up right here?
The Greek gets the first point, but Murray responds with his fifth ace of the match.
Laura Robson
Former British number one on BBC Radio 5 Live Sports Extra
This is such good tennis. It is really positive play from Andy.
*Murray 6-2 5-6 Tsitsipas
Not this time. Tsitsipas slams the door shut on Murray with a smash.
Murray 6-2 5-5 Tsitsipas*
Tsitsipas makes a positive start on serve, but Murray puts away a volley at the end of a well worked point to close the deficit to 30-15.
The Greek moves within touching distance of the game, only for a double fault to hand Murray half a chance...
David Law
Commentator on BBC Radio 5 Live Sports Extra
Andy Murray is going after the ball and trying to man-handle Tsitsipas in these rallies.
I did not expect to see that tonight.
Murray 6-2 5-5 Tsitsipas*
A great hold from Andy Murray to remain in contention in the second set. Any drop in concentration now from either player will be costly.
*Murray 6-2 4-5 Tsitsipas
A big miss from Tsitsipas opens the door for Murray, and the frustrated third seed miscues on the next point too. 30-30.
*Murray 6-2 4-5 Tsitsipas
Stefanos Tsitsipas gets on top in a baseline rally and forces the error from Andy Murray two move within two points of the set.
Laura Robson
Former British number one on BBC Radio 5 Live Sports Extra
Now surely Tsitsipas has got to feel that this is the time he needs to really commit to getting after these returns.
He has missed so many, especially on the second serve when they're pretty routine.
But he is dealing with a fired up Andy Murray who is moving so well so it is a difficult ask.
Tsitsipas needs a bit more energy,
Image source, Getty Images
Watson 1-6 4-6 Juvan
Heather Watson's US Open singles campaign is over.
The British 29-year-old bounced back a little in the second set but in the end Slovenia's Kaja Juvan claims a routine straight-set victory.
Elsewhere, Harriet Dart took a lengthy medical time-out in the second set against France's Caroline Garcia.
She is back on court now but Garcia has just taken the set to take it to a decider.
Image source, Getty Images*Murray 6-2 4-5 Tsitsipas
Murray survives one game point, but Tsitsipas secures the hold on the next as Murray goes long.
A huge game coming up now for Murray, as he serves to stay in the set.