Two sets all, two games all, 30 all.

That's what four and a quarter hours of action gets you.

@isanybody1: When Andy retires one day he should think about going into acting..maybe a thriller or Agatha Christie movie!

An ace from Nishioka and he certainly needed it. It's an ace to hold his serve and he's still looking in great spirits, smiling away loving his time on the Arthur Ashe Stadium.

Good character shown as he hasn't let those successive tie-break losses get to him at the start of this deciding set. Who wins this one? Tell us on Twitter using #bbctennis.

Andy Murray takes the opening point on the Nishioka serve. Can the Brit build on that?

Nishioka takes the next game, but Murray with a blink-and-you-miss-it hold to love.

Dan: One Andy Murray!

Dr Ros Clarke: I need to go to bed. I really need to go to bed. But Andy Murray is just into a fifth set decider. Gah.

Sleep can wait, Ros!

Murray is still fighting. He's just had to save a break point right away in the start of the fifth. Then he unleashes a perfect forehand from the middle of the baseline into the court and that helps him hold his serve.

Now, Nishioka is the one under pressure. How will he cope?

OK, so it is still on serve in the fifth, but Murray is now in the lead in this match.

David Law
BBC Radio 5 Live Sports Extra tennis commentator

Murray looked a shadow of himself. I thought if it's going to be like that, don't do it. That was perhaps naive given the sort of character he is.

He has proved over the past couple of weeks that there's still good tennis in him. He came out here flat. Nishioka was superb and was a worthy leader in those first two and a half sets.

Murray has scrapped, fought and dragged himself to 2-2.

Cameron Hume: Andy Murray putting me through All The Emotions at a Grand Slam again and I couldn't be happier.

Daniel Eckersley: Welcome back to Grand Slam tennis with Andy Murray. Have we missed this.

We're at the four-hour mark. We all wanted to see how fit Andy Murray is. This is our answer.

And also, it is a hot day in New York with the roof open and the sun beating down.

Naomi Broady
British player on BBC Radio 5 Live Sports Extra

We're constantly told to not pay attention to who the person on the other side of the net it. But it's so much easier said than done. When Nishioka has had the finish in his sights, he's lost his nerve a bit.

Right at the end of the fourth set, during the tie-break, Andy Murray stubbed his toe, although he still managed to win it to force a decider.

Now Murray is getting the toe taped up. Hopefully it will not hamper him too much in the fifth.

Francesca Gunn: Never count Andy out!! I knew he could get back in! Andy never goes out without a fight. That is what we are seeing.

John Poole: Ahhhhh an Andy Murray grand slam roller-coaster, it's been a while old friend

Rachel T: COME ON MUZZA!!!

Naomi Broady
British player on BBC Radio 5 Live Sports Extra

Nishioka is just so annoyed with himself. He worked incredibly hard and putting himself in a winning position and then he suddenly went: unforced error after unforced error.

Andy Murray's return to Grand Slam action looked like being a disaster. It looked like being a loss in three sets.

But never write off Andy Murray. For the second set in a row he wins it via a tie-break and it's into a deciding set. Great stuff.

Andy Murray. In a five-setter in a Grand Slam. How we've missed this.

Two set points have evaporated. A backhand nets. 6-4 Murray.

Murray was two sets down, 3-1 down and a break behind in the third, now he has set point to take us into a fifth. 6-2.

Murray now 5-2. Two more points and it's a five-setter. Just imagine the scenes if this court was packed, this would go down as a classic.

Murray extends his lead to 4-1, Nishioka claims the next point, but Murray still on top.

Naomi Broady
British player on BBC Radio 5 Live Sports Extra

Surely now this is the moment Andy can run away with it. At least this tie-breaker.