First to seven points in the tie-break wins the set.

Second seed Elena Rybakina, speaking on Court One after beating Lois Boisson: "It was a really difficult match. I was coming into this tournament off not too many wins, so I had to really fight. Hopefully the next round is going to be better, I need to improve quite a lot but I'm happy to get another opportunity. Thank you so much for coming, it is amazing to be back on this beautiful court.

"There were a lot of emotions inside. People who know me well, like my coaching team, they see when I'm stressed and when things aren't working. I'm glad I managed to get through, but I will definitely need to be better in the next round. I'm just looking forward to it now."

On what her coaching team said during the medical timeout: "My serve percentage wasn't the greatest so when she was getting good first serves in, it wasn't easy to break her either. The most important things were getting more intensity and moving my legs quicker because she was playing quite high which is quite rare on grass.

"They were just trying to tell me to keep on going, bring the energy and improve my footwork - and I'm glad I managed to do it all."

Image source, Getty Images

Harry Poole
BBC Sport at Wimbledon

The crowd inside court three rose to their feet as Toby Samuel forced a deciding fifth set against 15th seed Jakub Mensik!

The Briton waved his arm to the crowd, calling for more.

This is some spirit being shown by the world number 123 - and what a winner that was down the line when under pressure at 15-30 as he served for the fourth set.

After all the doom and gloom around Monday’s British performances, Samuel is a set away from delivering a stunning upset.

Ryan Harrison
Former French Open men's doubles champion on BBC Two

When you get to these later stages of the set, that's when those top players who are playing with a lot of confidence, as Zverev is, they will ask you the questions and not give you any easy mistakes.

Alexander Blockx plays a couple of drop shots of his own to get the better of Alexander Zverev, who scrambles in vain to dig it out and over the net.

French Open champion Zverev must now serve to stay in this second set.

Eugenie Bouchard
Former Canadian tennis player on BBC Two

It is great that Elena Rybakina was able to come through a match like this. It should give her the confidence that she can play well on the grass court and get back to her winning ways. Coming through a gritty three-setter is exactly what she would've wanted.

It has shown Rybakina and her team exactly where the holes are. Her level really dipped in that second set, she was throwing out a lot of unforced errors, but she knows that is what she has to work on now.

Alexander Blockx can't get a couple of Alexander Zverev serves in play, before being played off the court as the German second seed seals the game with a tidy drop shot at the net.

Image source, Getty Images

This is a straight shootout now on court three. A reminder that it is also the first ever time that Toby Samuel is playing a fifth set.

This must be equally as nerve-wracking and exciting for the world number 123.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 Live

It's hard to judge Rybakina on one match.

Her grass court form hasn't been that good - she was beaten by an inspired Katie Boulter at Queen's, and lost in the first round at Berlin.

She's genuinely quite hard to call and read and that's the thing with her. Her opponents say it's tough because she gives you no energy and she shows no emotion but it's hard to say with certainty, despite being world number two and a former champion, that she is a favourite.

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Alexander Blockx brings Alexander Zverev to the net with a drop shot before passing the German with a forehand winner down the line.

Blockx then clenches his fist in celebration as Zverev is unable to return a big first serve.

This set has tie-break written all over it at the moment.

Toby Samuel has taken French Open semi-finalist Jakub Mensik to a fifth set!

It seemed like the match on court three was only going one way after Mensik won back-to-back sets, but errors have started to creep in to the 20 year-old's game and he is becoming visibly frustrated by it.

That is taking nothing away from Toby Samuel though. His forehand when he was down at 30-15 was outrageous. It left Mensik speechless on the other side of the net, and Samuel cruised to the fourth.

Image source, Getty Images

Sam Smith
Former British number one on BBC One

Elena Rybakina survives a scare! The Australian Open champion gets her Wimbledon campaign underway, but there were moments where things were less than certain midway through that deciding set.

In the end, she pulled through and she might be better for it. She was certainly shaky in moments and I think there might be some buckets of balls out on the training courts in the next 24 hours or so.

Jeff Tarango
Former American tennis player on BBC Radio 5 Live

I thought this was Ben's year. He's been playing really great on the grass and I really thought Ben was the favourite for the United States and jeez, he's kind of surprised this happened.

You play a qualifier and you don't know anything about him but this guy earned it. It's not like Ben Shelton played badly, he played well and fought as hard as he could, but this kid - it's like a movie. It really is.

With the quality Virtanen played with, I think he goes on further, I don't think this is it.

Image source, Getty Images

Alexander Zverev works Alexander Blockx from left to right before sealing the point with a smash.

A couple of aces later and the German second seed sees off another game.

Both players are struggling to make inroads on each other's serve at the moment.

Ace. Ace. 30-15.

Lois Boisson stares down the court in disgust as Elena Rybakina's forehand kisses the line.

Two match points for the former champion.

Both players are continuing to serve well as the games speed by in this second set.

Alexander Blockx wraps up another hold with an ace with Alexander Zverev unable to do much about it.

Over to you, Zverev.

Lois Boisson saves the first break point and shakes out her left leg - the one she received treatment on midway through the second set.

Boisson saves the second and shakes out her right leg.

Boisson undercooks a one-handed backhand into the net. Elena Rybakina breaks.

Lois Boisson throws her head back in frustration after missing a first serve. Elena Rybakina climbs all over her second serve, sending back a booming return. Later in the point, as she scrambles to retrieve a backhand, Boisson takes a painful tumble.

0-40.

Image source, Getty Images

Eugenie Bouchard
Former Canadian tennis player on BBC Two

This really is a 50:50 match now.

Lois Boisson is a fighter. We saw that she is a competitor with her run at Roland Garros, but it just took her some time to settle into this match.

She definitely had to get used to Elena Rybakina's ball, which comes in hard and flat, as there are no players on tour who hit the ball like her. Just adjusting to that can take a bit of time, but Boisson did such a fantastic job of it in the second set.

She is absorbing the pace and staying in the rallies, which Rybakina doesn't like.