Murray gees up the crowd behind him as he steps back out on to Armstrong, looking for a vital break that keeps this match alive. Anderson eases into a 30-0 lead before the Briton puffs his cheeks out then pounces on a wide return to guide a backhand down the line. But that's as good as it gets for Murray, Anderson stepping on the gas again to level.

AG Ford: Armstrong's former home is just up the road from the stadium in Corona Park. Probably the area's most famous former resident.

Kvitova gets through, but you wouldn't know which is the world number five and which player is in a Slam fourth round for the first time.

Exactly what the doctor ordered for Murray - a routine hold. Talking of doctors, the Briton complained of feeling under the weather earlier in the tournament. Wonder if we will find out afterwards that he has not been feeling 100%. Not that we're trying to take anything away from Kevin Anderson, who has played superbly as he tries to reach a Grand Slam quarter-final for the first time.

Murray is a break away from taking this match to a fourth set...

Kvitova is one of the biggest hitters in the women's game, but Jo Konta is more than matching her. Kvitova, wobbly so far, gives away a second break point of the set with a double fault, but gets away with it when Konta trips to the net. Konta, though, gets another chance when Kvitova goes wide with a forehand...

Back to the action and Anderson, who flicked through a book of notes during the changeover, holds to 15. A smash puts him in position at 40-15 before a simple serve and return allows him to gallop to the net to crash down the winner with Murray nowhere to be seen.

Ashe is far from full as Johanna Konta skips on the line to get herself moving. Her serve is in good order early on, and the backhand isn't bad either. A brutal exchange with the black-clad Kvitova is ended with a skimmer down the line. Hold to 15. Are you sure you haven't been here before, Johanna?

Kevin Anderson doesn't strike me as the sort of character who would take pleasure in winding up an opponent. Maybe I'm wrong. The South African, who annoyed Murray earlier by taking an age to return from a comfort break, is not keen to rush back on court after the changeover. Murray gives him an icy stare.

Paul in Manchester: There's a lot of hyper-critical comments out there. Andy Murray has been one of the best players of the last decade. You can pick apart his attitude etc. But ultimately, he's losing to a guy who's served incredibly well and played some great shots on the big points. He's not played a bad match.

A hush around Louis Armstrong Stadium* as the Murray fans sense danger as the third seed trails 15-30. But a wayward backhand from Anderson brings Murray level, then the Briton hammers down a pair of aces to keep his nose in front.

* Anyone know why this tennis court is named after the legendary jazz trumpeter? I feel like I should be telling you the answer but I don't actually know...

Brett Curtis: Murray not in control of himself or his tennis at the moment. Even if he gets through this I think Stanimal takes him down

Murray might be bruised after letting that break slip - but his racquet is broken. The Scot slams his weapon into the blue acrylic with the power of a hammer hitting a nail. But the change of racquet doesn't really help as Anderson holds out to 15 to level.

Impressive in the early going from Konta, who is dressed in a red top and white visor. She holds to love. Nervous? Not so much.

Did you think that Petra Kvitova would wipe the blue New York floor with Johanna Konta? Think again. Konta passes to earn a break point in the very first game, but the two-time Wimbledon champion claws back a hold.

Anderson has looked a little lost over the past couple of games, but reasserts himself on this contest to force an break point. He begins to look like the same player who was hustling Murray with powerful and precise hitting earlier on. And it pays dividends as the South African wipes out Murray's break when the Briton goes wide - too wide - with a crosscourt forehand after a bruising rally.

Piers Newbery
BBC Sport at Flushing Meadows

"A huge moment for Jo Konta as she steps out into the biggest tennis arena in the world to face a double Wimbledon champion. Admittedly, the 23,000 seats are not yet full and, compared to the seething sweatbox of Armstrong, it's all very tranquil on Arthur Ashe Stadium right now. Petra Kvitova is sporting very bright pink trainers. They could put Konta off - they're hurting my eyes."

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

"He pointed to a fan across the stadium who is jumping up after every point. Andy is pulling all the fire out of this spectator who I don't think he has ever met before in his life."

What a turnaround! Andy Murray is back in business. Kevin Anderson looks to the heavens after gifting three break points to Murray by planting a close-range volley into the net. And the Briton snaffles his chance at the first opportunity, forcing Anderson into a rogue backhand that fails to trouble Murray's side of the court.

Stuart Mitchell: Murray is regressing as a tennis player, this is back to his old self pre 2012, since his golden period he's been a shadow.

Laus: Both times Murray has won the Rogers Cup, he didn't make it to the QFs of the US Open. Fatigue issue?

Murray screams louder than a child enjoying their first rollercoaster ride after nabbing that break point. He's happy.

And he continues the verbal release of energy with another ear-splitting roar after a vital hold. The third seed takes advantage of a drop of energy from the South African, bashing down two aces in quick succession to battle back from 30-15 down.