A break point for Kyle Edmund! I've been waiting almost three hours to write that.

Edmund tries to pin the South African back deep into the ad side corner of the court, but Anderson keeps responding to keep the Brit on the sideline.

Eventually Anderson is able to crack a forehand winner down the other side, but Edmund roars back to earn another break point. Like London buses...

And this time he gets it!! The first break point of the match comes at the perfect moment for Edmund...

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5

Five hours and seven minutes they played in that five-set Davis Cup semi-final last year and already we're thinking back to that.

If this set goes to a tie-break we could be looking at an 85-minute first set.

There's something about these two - they just can't help themselves.

Image source, Rex Features

You can hear the shutters clicking away furiously on the photographer's cameras as Murray contorts himself into his serve.

No-one's giving an inch but Murray puts his second serve to good use and holds with a lovely forehand that Del Potro is nowhere near.

Another timely reminder that the match between these two at the Davis Cup went on for five hours and seven minutes...

If someone's serve is going to buckle soon then it is going to be Kyle Edmund's.

The British number two is barely laying a glove on the South African when he has the ball in hand, while Anderson is asking serious questions from the receiver's end.

It is an interrogation.

Edmund goes 40-30 ahead with a trademark forehand down the line, only for Anderson to force deuce with super-duper cross-court winner.

But Edmund digs deep again and it is another hold for the Yorkshireman.

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5

This is the biggest player with the biggest game that Andy Murray has played since the first week off the season when he played Djokovic in Doha.

He's not played the big players because he's not gone deep into tournaments, so this is such a big day for Murray.

Saved! Murray feeds Del Potro's backhand again and it's back to deuce. No-one wants to end this game.

Fourth break point now for Murray as Del Potro's serve goes wonky, and he takes it with a clever winner! Murray goes down the line, Del Potro sprawls to meet in, and Murray taps the return beyond him.

Image source, Getty Images

Ooft. Murray gets on top of a rally, looks set to win it with a forehand, and he splices it long! And Del Potro has pulled it back to deuce! He serves so well under pressure and a 93mph forehand brings him back to parity.

Third break point comes up for Murray but he scuffs it, and now Del Potro has the advantage. Another big serve and he's got the first set wrapped up...

What. A. Shot. That's magnificent from Murray, lobbing Del Potro and the placement is inch perfect. A cracking return of serve puts Murray up 0-30.

Another defensive lob from Murray somehow lands on the line but Del Potro recovers brilliantly, forcing Murray into the corner of the court and he can only skew his return into the net.

It's two break points to Murray, though, winning another tussle at the net as Del Potro pats at fresh air.

Image source, Rex Features

A pair of aces isn't a bad hand to have, and Anderson decides to show it at the end of the seventh game in this third set. That ends any hope Edmund has of racking up his first break point.

Back to Edmund. And it's like Groundhog Day. I'm half expecting to see Bill Murray sat in Row A.

Anderson applies some pressure to the Brit's serve, earns another break point, blows his chance with an over-eager forehand past the baseline. Then Edmund makes the most of his reprieve with that power-drill of a forehand.

As you were.

Here we go, Del Potro serving for the set. There's a hush around the court as the Argentine steadies himself.

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live

We've seen the heavy artillery from Del Potro. He has one of the biggest games in the world and he's bullied Murray for most of this set.

There's such a contrast in style - it's like the fox and the hedgehog - Del Potro hits it like a howitzer while Murray is trying to move his opponent around but is being outpowered.

Image source, AFP

That is thunderous from Del Potro! All angles and power to Murray's serve, and the Briton has no choice but to watch another forehand go fizzing beyond him.

Murray goes big on his own serve in response but Del Potro's not having it. He's moving about constantly, recovering from a sprawl to hammer a winner beyond Murray. Murray gets lucky, though, as Del Potro spoons his return high and wide. Deuce.

Murray recovers, though, first with a forehand winner, then a backhand to hold.

BBC Radio 5 live

There's commentary available from 5 live of Murray v Del Potro, which you can listen to using the player at the top of this page.

Another Edmund service game, another back-to-the-wall job for the blond Brit. Anderson racks up another break point, his seventh of the match, again he can't convert as Edmund wriggles free.

Even Wayne Rooney has a better conversion rate than Anderson. Sorry Wayne, cheap jibe.

Image source, AFP

Ooft. The first break point is served with a casual 110mph serve from the Argentine, and the next serve goes crashing into the corner of the court.

It's such a strong part of his game and that's clever tactics from Del Potro. He serves out the game, mixing up his speeds and his lines.

That's better from Murray, one foot in the air and a spinning backhand drop shot beats Del Potro. The Briton keeps pushing, meeting Del Potro's big serves, and now he's got two break points to play with...

Image source, Getty Images

Hold, hold, hold. On it goes. Kyle Edmund has not had any of the six break points in this match so far - and he ain't getting one here. Kevin Anderson serves out to love.

Image source, EPA

Murray knows he can play on the weaker bit of Del Potro's game - the backhand - but the Briton is soon turning around in circles as another forehand goes firing past him.

A grunt and an exclamation from Del Potro as he spoons a low return out of play, breaking the impasse, and he completely spoons his return! All his annoyance went into that and it's not worked for him, the ball flying high over Murray's head.

Image source, AFP

Man, Del Potro's forehand is good. Despite the wrist injuries there's still plenty of fizz in it and Murray is beaten for pace.

There's some cracking stuff up at the net, too. A slightly unimpressive volley hands Murray a point but Del Potro has the best of a frantic rally, hammering a forehand to the right and leaving Murray rooted to the spot. If you can hammer a forehand elegantly, then Del Potro's done just that.

Some serious wheels on show.

Image source, AFP

More bottle than your local recycling centre! Kyle Edmund looks to be getting mangled when he coughs up THREE break points, but escapes when the crushing machine that is Kevin Anderson when he fails to convert.

Edmund battles back to deuce, Anderson handing over the game when he miscues a forehand return. A South African-accented yell of frustration greets the end of that game.

Chance gone.