Tsitsipas finds the line with a passing backhand to close to 40-30.

A big point for Murray here, and it falls in his favour as Tsitsipas goes long.

He's taken the world number three to 5-4 in the fifth and the Greek will have to serve this out...

There's no room for error for Andy Murray.

A 30-0 advantage eases the pressure for now.

Henry Clarson: 'Mon the Murray! This is NOT over yet.

David Law
Commentator on BBC Radio 5 Live Sports Extra

This is such a physical battle.

It's too good from Tsitsipas, who whips a forehand down the line for 30-15.

Murray nets and gives himself a telling off for good measure. He can't stop the Greek on this occasion. 5-3.

Can this be the game for Andy Murray? He's come close in Tsitsipas' last two service games, but he needs to make it count now.

What a response. Andy Murray cruises to a love hold.

Laura Robson
Former British number one on BBC Radio 5 Live Sports Extra

It's a tough couple of games as an Andy Murray fan but you have to say Tsitsipas has played excellent when it matters.

Again and again he has delivered.

Ian B: If this goes the way of the Greek, Murray will lose nothing in defeat. The standard he's maintained for five sets in these conditions has been phenomenal.

Georgie Heath: It’s a sign of just what a competitor Murray is that we still all believe he could win this. He’s the definition of “it ain’t over until it’s over” and he always gives everything right down to the last. A true great.

Laura Robson
Former British number one on BBC Radio 5 Live Sports Extra

How good is Tsitsipas playing under pressure?

Every single time he has been down in this fifth set he has delivered.

Another impressive hold under pressure by Stefanos Tsitsipas.

Andy Murray is still complaining about the length of the Greek's earlier bathroom break but he needs to shake that from his mind right now.

Another big service game coming up.

Oooft. Just long by Murray, who requests a replay. Tsitsipas seemed very sure as he left it and is level at 30-30.

A forehand winner turns the game in the Greek's favour, but Murray puts away a backhand for deuce. Another chance.

A poor miss from Tsitsipas at the net is followed by a complete mis-hit.

Murray leads 0-30...

A big first serve from Murray sets him up nicely for 40-15 before securing a comfortable hold.

Now, can he push Tsitsipas all the way again?

Sam Shatterface: Desperately unsporting from Tsitsipas to take as long as he did in the toilet but Andy’s played right into his hands by letting it get under his skin. Such a great champion should know better.

Andy Murray is not the only Briton in action in New York currently.

British number two Cameron Norrie's match has just begun. The 26th seed is facing world number 55 Carlos Alcaraz and it's on serve in the first set.

Tsitsipas turns to crowd in celebration as a forehand winner rescues deuce, before the Greek battles back admirably from a tricky situation to hold.

Image source, Getty Images

Murray, as he does, digs deep and a Tsitsipas shot travels long after clipping the net.

It's a break back point to the Briton!

We're approaching four and a half hours on court but Andy Murray is still darting around the place. It's wonderful to see.

Tsitsipas misses on his opening point, but consecutive aces turn the game in his favour. 30-15.

A must-hold here for Murray, you feel.

A cool backhand winner moves him clear at 40-15, and a smash at the net ensures he does just that to stay within striking distance.

Image source, Getty Images