If it's deemed that the electronic line calling system is faulty there are a team of humans waiting to come out and offer an old school alternative.

For now it seems the system is working.

Cameron Norrie and Nicolas Jarry are walking out on to Court One as they prepare for their fourth-round match.

Norrie has endured a difficult few years since reaching the semi-finals at Wimbledon in 2022.

He climbed as high as eighth in the world three years ago but he is now 61st, with injury and poor form dropping him down the rankings.

But the Briton appears to be on the comeback trail and is keeping opponents on their toes with his playing style.

Jess Anderson
BBC Sport at Wimbledon

"The electronic line calling system was unable to track the last point so we will replay the point."

Eek.

Jess Anderson
BBC Sport at Wimbledon

Image source, Reuters

Talk about happening at a crucial time!! Sonay Kartal stands with her hands on her hips as the umpire sits in his chair on the phone.

She then perches herself on her racquet and stares down the umpire.

This is far from ideal isn't it.

Jonathan Jurejko
BBC Sport senior tennis reporter at Wimbledon

The excitement levels are bubbling up nicely on Court One.

This is Cam's court.

Norrie loves playing out here, having won three of his matches to the 2022 semi-finals on Wimbledon's second show court.

Expect a partisan atmosphere, of course, but there will also be a few Chileans making themselves heard.

Already spotted two groups in front of me with Chile football shirts.

Jess Anderson
BBC Sport at Wimbledon

Oh my goodness. Well we've heard chatter all week about whether the new automated line calling system is accurate, if it's loud enough etc etc.

And now the umpire has stopped the match while he checks whether the AI is working because the ball looked clearly out and no call was made.

Anastasia Pavlyuchenkova is so smart in the way she saves break. Sonay Kartal doesn't read the drop shot and it bounces twice before she can even swing her racquet.

A serve and volley gets advantage for Pavlyuchenkova.

What do we have here?

Pavlyuchenkova thinks Kartal has put her forehand long and is waiting for the call as the Briton slams a winner at the net.

The umpire has halted the game and is on the phone speaking to the electronic line calling team to see if the system is working.

Replays show the ball was out but we are still waiting for an official verdict.

Image source, BBC Sport

Anastasia Pavlyuchenkova gets to advantage but then faults on first serve as she looks for the hold.

The Russian has only won one point on second serve and that statistic continues to stand when she puts into the net for second deuce.

Pavlyuchenkova can't keep it in and Kartal has a third shot at break point.

Sonay Kartal gets too much on a backhand and it lands in the tramlines.

The Briton is forced wide on Anastasia Pavlyuchenkova's serve - her fastest of the day at 110mph - and can't come up with a return again.

Leon Smith
GB Davis Cup captain on BBC Radio 5 Live and BBC Sounds

That double fault is an absolute bonus at this time, isn't it?

Sonay Kartal is showing good body language here, just bouncing around and getting ready very quickly in-between points.

Image source, Getty Images

The noise levels have just gone up a notch on Centre Court as Sonay Kartal earns two break points.

Tracy Austin
Two-time Grand Slam champion on BBC One

There is such a contract in styles here. Kartal is consistent and you know what is coming. Whereas Pavlyuchenkova is streaky and very hot and cold.

Pavlyuchenkova is on the move with each shot at the moment.

Naomi Broady
British player on BBC Radio 5 Live and BBC Sounds

The biggest benefit for this match-up in game styles is that Anastasia Pavlyuchenkova's forehand is her weakness. That is the side that is going to break down and Sonay Kartal loves her cross-court forehands.

So if she can keep attacking on that side, and I wouldn't even mind seeing some of her second serves going onto the forehand, then I think she will get more from the ball.

Image source, EPA

After a fourth deuce, Sonay Kartal finally finds enough to put a couple of points together for the hold.

We've had four holds and four breaks in this opening set.

Highly entertaining but no clear idea as to how it will conclude.

Anastiasia Pavlyuchenkova's 20th unforced error hands advantage to Sonay Kartal but the Briton is dragged back to deuce.

It looks like we've got another scrap on our hands for this game too.

Sonay Kartal has the new balls in hand for this eighth game.

Kartal gets over a high ball on the baseline and emphatically finds the corner for 40-15.

The 23-year-old can't close out the hold and is taken to deuce.

Image source, Getty Images

We were hoping to have play resume on the outside courts very shortly, but the latest we are hearing is there will be no play until 14:30 BST.

The sunshine does appear to starting to come through so fingers crossed action will be back under way soon for those courts without a roof.

There were emotional hugs with his family for Nicolas Jarry as he celebrated reaching the fourth round at Wimbledon after a "year of battles" with his eyesight.

It was a significant moment for the Chilean world number 143, who plays Cameron Norrie - the last British player left in the men's singles - in front of what will be a partisan Court One crowd today.

Just over a year ago, Jarry woke up and could not open his eyes, struggling with a persistent rolling sensation that affected his vision.

It was not the first time he had experienced it - but this time, it was worse.

The 29-year-old was suffering from vestibular neuritis,, external a condition caused by inflammation of a nerve that connects the ear to the brain.

Symptoms include the sudden onset of vertigo, dizziness and difficulty maintaining balance.

"I remember that I was trying to type in my phone and I couldn't," he told the BBC.

"I couldn't open my eyes because everything was rolling so much.

"I started crying immediately, to lose things that are so obvious, so natural."

Image source, Getty Images

The game ticks over eight minutes when Sonay Kartal fails to capitalise again.

Kartal is forced wide on the serve and her cross-court return finds the net.

The net cord sets the ball up high for Kartal to attack but the Briton can't get it back over and Anastasia Pavlyuchenkova finally seals the hold.

Anne Keothavong
Former British number one on BBC TV

The drop shot is a clear tactic of Pavlyuchenkova and she is using it wherever she can. But Kartal is dealing with that shot well at the moment.

Pavlyuchenkova doesn't want to get into too many baseline exchanges with the Brit.

Image source, Getty Images