Cathy Bruce: Thank you, Jonathan, for letting me feel I'm actually at Flushing Meadows, when I'm really in cloudy Essex.

While Anderson toiled with the ball in his hand during that last game, Murray fares much better. A wonderful double-handed backhand from the South African - quite a rarity - is brief respite, only for Murray to slam down his fifth ace of the match to maintain a slender advantage.

Meanwhile, we see a tanned Frank Lampard - of course plying his trade with New York City FC - sitting in the Murray box with his partner Christine Bleakley. Not a bad freebie....

Image source, Getty Images

Ian Bradley: Murray generally lauded for his defence but faint praise, best in world at returning good shots with interest

Now then - Murray has another break point. The Briton is being worked hard in the stifling heat, scurrying across the baseline, but misjudges a forehand to let Anderson off the hook.

Anderson then puts himself back within a point of the hold, before hitting the self-destruct button again with a shank. That hands a third chance for Murray but then he gets a little heavy with the racquet as another break point goes begging. Anderson claws his way into another advantage, finally dragging himself across the line as a deep return cannot be belted back by the Murray backhand.

Piers Newbery
BBC Sport at Flushing Meadows

"There is a bit of a breeze on Armstrong which just about takes the edge off a baking hot afternoon, and the stands are packed for this one. The queue of those still hopeful to get in stretches all the way back to Ashe several hundred meters away. The good news for the players is that, at approaching 5pm local time, the sun is dipping towards the back of the stand."

Image source, Al Bello

Murray is left standing motionless as another Anderson arrow whizzes past his eye line. But the 15th seed offers a reminder that his all-round game doesn't quite match the big boys, an unforced forehand error letting Murray back in. Anderson has another chance after Murray wrongly challenges a return that dusts the baseline, but blows that one too. On we go...

Jiten Chandarana: What are the chances of Murray getting annoyed at least once about the backdrop (or lack of) behind the baseline or spider cam?

After a quick gulp of ice-cold water, the pair saunter back into the New York sun. Murray, standing well behind the baseline, sticks his strings on each of Anderson's first two serves to put the pressure back on the South African. Anderson claws himself level, only for a mistake to offer up an early break point to Murray.

Anderson unleashes another speedy serve, going to the Murray backhand, which is unable to guide the ball back over the cord. Deuce...

Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

"Each guy is going to get a couple of opportunities to pounce and whoever deals with that best will will win the match. It will be millimetres. Andy is staying calm, taking on fluids. This is a distracting court, people coming in and out, rock n roll music playing. You have to be focused to win here."

Murray looks pretty pleased with himself at the first changeover - and rightly so. The third seed's service game is impeccable in these early stages, pinning Anderson back on the baseline as he cleans up a hold to 15 with a second serve ace.

Don't worry, the Anderson serve has arrived. The South African goes big from the off, tearing down a 136mph serve to open his ace account at the first attempt. Murray calmly wipes his brow, that's not something he wasn't expecting. The Briton hauls himself back to 30-30 but Anderson ups the tempo again, leaving his opponent unable to make another dent on his service game.

Perfect start for Andy Murray - a booming ace down the T. Another ace, this time out wide, puts him 30-15 ahead before Anderson clubs a return wide. A weak return gives Anderson a slight sniff, then the Briton pulls another ace out of the bag for the hold. Hang on, isn't it the Anderson serve which is supposed to be the big weapon?

Andy Murray ties the shoelace on his eye-watering luminous yellow trainers, hooking his wedding ring around the cotton as is now his tradition. The Briton to kick things off...

* Denotes next server

Image source, Getty Images

Like Johanna Konta, Kevin Anderson is wandering into unknown territory. The South African is appearing in the fourth round at Flushing Meadows for the first time and aiming to reach his first Grand Slam quarter-final.

The problem is that third seed Andy Murray is staring back across the net at him. The Briton has a 5-1 winning record over Anderson, including three successes on hard courts.

"Obviously it would mean a lot," said Anderson on the prospect of reaching the last eight. "I've been in the fourth round a few times but it's my first time here and it's obviously a small step in the right direction."

Image source, Getty Images

You would imagine that a tennis player standing 6ft 8ins tall knows how to hammer down some nuclear-strength serves. And you would be right. Kevin Anderson has hammered down 69 aces in New York so far - only Marin Cilic has clocked more having played a match more - and is high on the leaderboard for first serve points won and service speed.

But Murray has one of the best defensive games on tour - and is not fazed by Anderson's armoury.

"Getting a lot of returns in play is something that throughout most of my career I've been good at," said the Briton.

"Often the big servers come into matches used to getting a lot of free points. It changes their mindset a little bit in the way they play the match and play the points."

First round: Murray 7-5 6-3 4-6 6-1 Kyrgios

You've probably heard a lot about Nick Kyrgios - not necessarily about his tennis. The talented but temperamental Aussie had a go at third seed Murray, only for the Briton's greater quality and experience to shine through.

Second round: Murray 5-7 4-6 6-1 6-3 6-1 Mannarino

No-one expected this one to go to five sets. Possibly not even France's Adrian Mannarino. Murray had not lost in the first week of a Grand Slam since 2010 and continued that fine record with a gutsy win.

Third round: Murray 6-3 6-2 7-5 Bellucci

Would that gruelling comeback against Mannarino leave Murray sapped in his next match? Not a chance. The Scot breezed through in two hours and 11 minutes against the Brazilian.

The New York weather can be described in a way that us Britons can only dream of seeing here in Blighty. Hot and sunny. Probably a bit stuffy for some sun-shy Britons mind. Murray is decked out in a sweat-reducing white t-shirt, with a baseball cap for added protection. Sensible.

Ever wondered how Murray warms up for a Grand Slam match? By lobbing a tennis ball across the Flushing Meadows car park to his fitness coach Matt Little. Shortly after that little game of catch, Murray wanders out on to a sun-soaked Armstrong, where a sell-out crowd whoop enthusiastically as he arrives. Anderson, the 15th seed, is greeted warmly - but the noise level is much further down the decibel meter.

Anyway that's enough Konta-related chit-chat for now. The Briton and her Czech opponent will be strolling out of the locker room about 00:00 BST for their clash on Arthur Ashe Stadium so we will talk more about that match a little later on.

Now we are heaping our undivided attention on another patch of blue acrylic about a stone's throw away from Ashe. That's because Andy Murray is about to kick off against Kevin Anderson over on Louis Armstrong Stadium....