A change of outfit for Nishikori. He replaces a sweaty scarlet top with a toothpaste white number. Cool and fresh and ready to go. Well, sort of. The cameras go in search of Boris Becker, who is squinting in the sunshine. The intensity has dropped a touch as both players attempt to conserve energy. A hold to love for Djokovic. The lifeless Nishikori not bothering to chase the final serve. On this showing, it won't be long until he starts seeing mirages.

Image source, Getty Images

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"This reminds me of Djokovic's fourth set versus Murray - Djokovic can see that his opponent is slightly lame but not so lame that he cannot produce some stunning winners."

As Nishikori prepares to launch another howitzer towards Djokovic, a lady in the background is fanning herself in the oppressive heat. Brutal conditions for spectators and players alike. The canny Nishikori keeps the points short and comes away with a hold to 30.

Alex Haworth:, external "Nishikori looks fried. I think the heat is beating him more than Djokovic is."

Djokovic dragging his opponent towards the net with a cushion-soft drop shot from the baseline. Nishikori then forced to backpedal as Djokovic attempts to lob him... The Serb's execution isn't perfect but Nishikori messes up the backhand overhead. An intriguing opening point.

Djokovic's serving too potent for Nishikori and the Serb skips merrily to 40-15. A needless error from Djokovic, though - pushing a volley wide - and is it a whiff of a sniff for Nishikori? The 10th seed rolls the dice with a loose-limbed forehand return, but it is a touch too loose, a touch too wide.

Image source, Getty Images

Fabulous from Djokovic - racing towards the barrier to fetch another dodgy Nishikori drop shot, unleashing a formidable deep volley. The Serb like a shark smelling blood - two break points Djokovic.

But, suddenly, Nishikori morphs into Martin Brody, seeing off the great white with a volley at an irretrievable angle and, then, he forces Djokovic into a cul de sac and beats him with a backhand down the line. Bravo. To deuce we go.

During a topsy-turvy eight minutes we flow from advantage to deuce to break point. A perfect return from Djokovic and he raises his arms, calling on the fans to increase the noise, and they do. There's also a double fault from Nishikori - the first of the match.

Otherworldly tennis from both players. Breathless stuff. Trainers screeching, fans screaming... will it ever end? Yes, yes it will. Nishikori scrambling over the line, bitten by his predator but Djokovic unable to inflict a mortal blow.

Image source, AP

Piers Newbery
BBC Sport at Flushing Meadows

"My phone has just sent me an 'alarm' notification with a symbol of an umbrella. I'm no meteorologist, but that doesn't look good. All is well above us right now but if one of these two can get through this semi-final uninterrupted, they might get an advantage if the second semi is delayed."

Image source, Reuters

Nishikori going toe-to-toe (or is that racquet-to-racquet) with Djokovic on the baseline, but the Serb is absorbing the 10th seed's biggest punches and the man from Japan messes up the point with a lame drop shot. But the dark horse is soon fist-pumping thanks to a winning forehand into the corner. 15-15. Djokovic gallops to 40-15, though, with an unreturnable bazooka, followed by a well-timed serve volley. Nishikori's defence made of tissue paper, a return drifting long, and that is that. No more to see here.

Russell Fuller
BBC tennis correspondent at Flushing Meadows

"It is so important Nishikori stays with Djokovic in the early stages of this third set - otherwise this match could run away from him very quickly."

A change of racquet for Djokovic for the start of this third set. A floated forehand from the Serb curls inside the court for a wonderful opening point, but Nishikori is unfazed and secures a confidence-boosting opening game.

Image source, AP

Cool and crisp serving from the world number one and after one hour and nine minutes, we're even stevens. Djokovic concludes the match with a stylish ace, his sixth of the match.

Djokovic has flicked the switch and his engine is now roaring. The Serb dominating from the baseline - and collects two break points for his efforts. A casual-looking return into the tramlines from Djokovic. Nishikori battles to deuce. But from advantage he fails to connect with an attempted forehand and follows up with a forehand into the tape. Third break point Djokovic. The Serb pounces on a tame drop shot and the top seed's killer instinct has returned.

Image source, PA

Fortune favours Nishikori, his forehand clipping the net and not even Djokovic, scooting towards the tape like a panther, can fetch the ball. A sniff for the underdog at 15-30. Top seed Djokovic grunting and groaning from the baseline... but he gets Boris Becker off his seat with a dazzling drop-shot from the back of the court. The crowd applaud in approval. A clinical game from Djokovic, with a touch of showmanship too.

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"Not a great game from Kei. We talked about the up and down after the number of sets he has played in the last few days. He hit some very makeable shots wide in that game."

Image source, AP

Djokovic stepping in from the baseline, whipping a forehand down the line for a 30-0 lead. Should Nishikori fans be shuffling uneasily in their seats? Yep, I'm afraid so. Nishikori steals one point but goes long on the next to gift two break points to Djokovic and the 10th seed presents the game to his opponent with a cherry on top, screwing a forehand into the tramlines from the back of the court.

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"If I was in the Djokovic-Becker camp right now I'd be worried. He's at risk of going 2-0 down here with Nishikori just going for it. However, if Djokovic gets this one you would still fancy him to do it."

Image source, AFP

Alex Haworth:, external "Would love Nishikori to make a good game of this. Great start from him."

Toni:, external "Little hiccup from ND. Don't read too much into it! Kei will learn from this & he'll be better for it but he's going to get schooled!"

Pin-point accuracy from Nishikori, a thunderous crosscourt winner sending Djokovic onto the canvas. 15-15. But Djokovic's knees are not for buckling and he's soon back on his feet, keeping the points short and ending the game with a crackerjack of a forehand winner.

At 30-30, this game could swing either way but Djokovic isn't retreiving with his usualy gusto. Nishikori sending Djokovic lunging from tramline to tramline until the Serb can take no more and he goes long. Nishikori follows up with a fine first serve and there's no sign of Nishikori's sparkle dimming.

Image source, Getty Images

David Law
BBC Radio 5 live commentator

"Nishikori weighs just 10-and-a-half stone, yet he packs a punch that belies that relatively diminutive size."