Just! Dan Evans catches the line with a forehand. Popyrin makes another attempt to stick away a volley but knocks it wide and another miss completes a welcome hold to love for 24th seed Evans.

Now it's Popyrin's turn to show some real emotion.

Evans takes the Australian to deuce but Popyrin claims the hold with a volley at the end of another thrilling rally. A clenched fist and a roar to the stands follows.

Love that! Dan Evans clips a lob over Alexei Popyrin for 15-30 and has a little joke with his team in the stands.

Popyrin doesn't let that point get to him, though, and puts away a smash for 40-30.

Both players are maintaining a really high level as we reach three and a half hours of play.

A Dan Evans drop shot leaves Popyrin chasing shadows and an ace helps the Briton to a love hold. On we go!

Popyrin dominates on serve with a couple of aces to quickly put the pressure back on Evans as we approach the business end of fifth the set.

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

I was almost on my feet then. To be at 2-2 in the fifth... both players are finding something extra in the tank and it is amazing.

Evans turns things around and a stunning cross-court forehand clinches a massive hold of serve for the British number one.

Wide from Evans. Break point to Popyrin. The court 17 crowd hold their breath. A big moment.

While we remain on serve, Evans will be playing catch up in this fifth set.

'Come on' Evans shouts, as Popyrin hits wide of the mark. But the pressure is soon back on as the Australian takes the opportunity to close for a volley. 30-30.

That is the point of the match right there.

Evans tests Popyrin with a lob, and then a shot out wide, but the Australian recovers on both occasions to slot an angled backhand past his opponent for 30-30.

And from 0-30 down, Popyrin draws on that adrenaline rush to hold. Great stuff.

A huge roar from Dan Evans!

The Briton whips a forehand past Popyrin for 0-30.

Whatever you can do...

Dan Evans responds with a hold to love of his own.

No sign of fifth set nerves creeping in on serve just yet.

But who will have the most left to give?

Alexei Popyrin lets us all know he's feeling good after a little rest with a rapid service game. Evans can't land a punch.

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

I almost can't pick it - it is basically who has enough left in the tank?

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

The way Popyrin was playing in the first two sets, I didn't think Dan would have enough to get through. Physically, he looks gone. But he is a fighter and he's still playing the tennis that suits him.

We're going to a fifth set on court 17!

Dan Evans comes out on top in a rollercoaster set to come back from two sets down in New York. Outstanding effort.

Popyrin can't get a return back. Two set points to Dan Evans.

Here we go then.

Popyrin certainly won't give up the set without another fight. Evans hits wide, but the Briton sprints forward to put away a couple of volleys for 30-15. What tiredness?!

David Law
Commentator on BBC Radio 5 Live Sports Extra

Both men look like they're going through a horrible experience.

This fourth set is dizzying!

A fifth break of the set - and it means Dan Evans is now one hold of serve away from forcing a decider.