Jeff Tarango
Former professional tennis player on BBC Radio 5 live

"Andy Murray looks like he's in a lot of pain. He's walking around like I do first thing in the morning when I'm trying to find my toothbrush. It's 80% mental, but he's really exhausted. Those first two sets were gruelling."

What have these two got left? Can they continue to hit the glorious peaks of the previous three sets. Yes, yes they can. Probably. A lengthy rally ends with a Djokovic backhand going long. Ben Stiller, he of Hollywood films, applauds their efforts. The Serb digs deep, saves a break point and skips ahead after a hoicked Murray forehand and an ace.

Russell Fuller
BBC tennis correspondent at Flushing Meadows

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"Amelie Mauresmo said she sees no reason why Murray can't win - even if he may not be at his best until 'towards the beginning of next year' when he's 'completely fresh and ready'.

"Murray was very fired up during his win over Jo-Wilfried Tsonga, often pleading very emotionally with himself to raise his game. 'I haven't really made up my mind on this yet,' said Mauresmo. 'He's old enough now to know what's good for him, how he should behave on the court, what brings him energy and what maybe is taking him down a little bit sometimes. It's not going to be either saying nothing or completely going crazy on the court - he has to be in the middle somewhere'."

Murray was in control at 30-0, but he puts too much power on a forehand, follows up with a netted forehand and then a net chord goes Djokovic's way. Set point. Danger averted thanks to a punchy shoulder-high volley. Backhand into the tape, though, and Djokovic has a second set point. And Murray must take this match to a fifth set if he is to progress to the semi-finals. Another mistimed backhand and Djokovic is ahead.

Murray giving his best impression of a character from One Flew Over the Cuckoos Nest, muttering to himself after netting a return. A tango at the net, replays show Djokovic's volley was a fraction wide. But from 15-30 to 40-30 we go. Murray's return bounces beyond the baseline. Djokovic a game away from winning the set.

Djokovic gobbles up a 73mph second serve, but Murray responds positively. Big serves. Big points. A hold to 15.

Murray steps in to crunch a backhand return onto the line for 40-30. What a returner Murray is, sending up a moonball and Djokovic miscues the overhead. Deuce! Another Djokovic error presents Murray with a break point. The pair start of with a series of fierce exchanges and then they slice and dice it, with Murray going long on the 27th shot.

A second break point comes and goes. Brilliant from Djokovic as he wriggles free. Has the landscape changed?

Kate MacKenzie: "Have to be up in an hour or so... finish it off Andy and get my day off to a great start!"

Richard Lismore-John: "Murray's forehand, his weaker side, is starting to dominate from the baseline - encouraging signs!"

Christopher Halsall: "It's hard to keep track of the constant changes in momentum in this game. It's with Murray now and he's got to make it count."

It's midnight in the Big Apple, but if you're in Britain there will soon be breakfast TV to watch. Djokovic nicks the opening two points - a Murray backhand drifting long to get the doubters talking. But dealing with the Murray forehand is like trying to contain lightening in a bottle and he saves one point. Ah. But, having typed that, the forehand falters - two break points Djokovic. Murray backhand long. Djokovic, somehow, runs free.

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Djokovic proceeds to 40-15 and an unhappy repeatedly says "furious" while glancing towards his team. The Serb ahead once again.

An inch-perfect crosscourt forehand from Murray forces Djokovic to nearly do the splits. The Serb rattled and understandably so because there are exquisite shots coming from the Murray racquet. A scintillating forehand winner follows for a hold to love.

Floodlights at full beam, lighting up Ashe, but the players generating enough wattage to illuminate if there should be a power cut during this high-voltage. A number of empty seats to be seen as spectators take this opportunity to stretch their legs. Oh, and it's a comfortable hold for Djokovic.

A fine first serve from Murray down the middle and Djokovic's return dribbles into the net. Second set to Murray. I wasn't planning on sleeping tonight anyway...

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Murray senses Djokovic's fuel gauge is running low so he ups the intensity, pulls the Serb around the court like a fine puppeteer until the top seed nets. 5-1 Murray at the changeover.

Ear-splitting cheers on Ashe as Murray secures the first point. The Scot collects another and Djokovic looks like he could do with spending some time in a countryside retreat to recuperate as a tired forehand into the tramlines gives Murray a 3-0 lead.

Murray the marathon man, coming out on top of a 23-shot rally. Djokovic in trouble, he's 4-0 down. Time to send up the flares?

Scott: "This is an unreal match. Supporting Murray from back in his home country of Scotland. Do us proud, lad!"

Alex Antiff: "Work in 3 hours... sleep is overrated anyway."

Anon: "Each set is like a match between these two. Djokovic may have won the battle but Rome wasn't built in a set."

Murray has spent three and a half hours longer on court than Djokovic in this tournament, but the Scot showing no signs of fatigue. Immense power and accuracy from Murray as his forehand forces Djokovic wide. From 15-15 to 30-30 and Murray senses his opportunity is now.

Relentless stuff from Murray and Djokovic crumbles like a chocolate flake, backhand long for a break point. But if Murray is to stop this set from going into a tie-break he must do that all over again because Djokovic drags the game to deuce.

Has Murray blown it? An attempted lob goes long, Advantage Djokovic. Another lengthy rally ensues. Djokovic into the tape. Deuce. Advantage. Deuce. Advantage. Murray nets a forehand. Into a tie-break we go.

Piers Newbery
BBC Sport at Flushing Meadows

"The Murray backhand has always been his favoured side but 'the Lendl years' saw his forehand become a real weapon, and for the last few games it has been dominating. Some thunderous flat strikes into the corner have had Djokovic scrambling beneath us in frustration, and looking to his team for answers.

"The question is, can Murray keep belting those forehands for another two hours or more?"

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Murray rattles off three points in quick succession and nudges ahead with a crisp one-two - a forehand out wide followed up with a clubbed forehand winner.

This set has not been as mesmeric as the first, but it is intriguing nevertheless. Not even a peek for Murray on the Djokovic serve as the top seed holds to 15.

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