A brave move by Carol Young Suh Lee to make her way to the net and she gets her reward, slamming down a winner.

But Boulter finds her forehand again and the American can only fling her racquet at the ball.

Katie Boulter saves the break point and then comes up with a massive serve to help save another one.

Now the British number one has the chance to see out the set.

The forehand had been working wonders for Katie Boulter, but she misses another one in this game and Carol Young Suh Lee has the chance to break back.

Heather Watson
British tennis player on BBC Radio 5 Sports Extra

Those two forehands Boulter has just missed is uncharacteristic of her. I think that's a bit of nerves and also just the pressure that Lee continues to put on her.

Katie Boulter has looked fairly comfortable on serve, but now, when the pressure is on her to serve out the first set, she finds herself 0-30 down.

Now it's Carol Young Suh Lee's turn to land a double fault at 40-0 up.

That's the only blip, though, and she'll make Katie Boulter serve for the opener.

A bit of a wobble from Katie Boulter there, but she recovers well and lets out a huge roar of "come on" as she gets the hold and moves one game away from taking the first set.

Image source, Getty Images

Katie Boulter whizzes to a 40-0 lead on serve before a double fault stops her momentum. And there's another! Deuce.

Carol Young Suh Lee holds her nerve to win the next three points and get another game on the board.

Katie Boulter missed the chance to go a double break up earlier in the set, but she can have another go here as Carol Young Suh Lee nets.

Heather Watson
British tennis player on BBC Radio 5 Sports Extra

Katie's got a lot of positive energy bouncing around. There was a big 'come on' after that point. I love her positive body language, I really admire it and I try to use it myself sometimes.

Carol Young Suh Lee hasn't had it easy in her service games.

A flick of the wrist and Katie Boulter lands another stunning forehand winner to bring us to deuce.

Heather Watson
British tennis player on BBC Radio 5 Sports Extra

Katie is having spells of playing a few great points in a row, playing aggressive and hitting her forehand, finding the court and then she'll just have a few where she'll have a few wild misses.

When she can start lining those points together, she's going to start steamrolling.

Katie Boulter's game is very much 'go big or go home'. And when it works, there's not much you can do to stop it.

Three huge winners and then a booming serve that Carol Young Suh Lee can only push into the net.

Image source, Getty Images

It was looking like a straightforward service game for Carol Young Suh Lee after she raced to a 40-0 lead, but Katie Boulter makes it a little tricky and pulls back for 40-30.

The 24-year-old American stays composed, though, and gets the job done by dictating play from the baseline.

Katie Boulter twice falls behind and twice claws her way back to grab a hold and ensure she maintains her break advantage.

Katie Boulter has just got married, and her husband Alex de Minaur is watching on from the stands, but there's no sign of a wedding ring!

The British number one said earlier this week that she would not be wearing it on court and joked that she had learned from Andy Murray's infamous mistake. The three-time major winner lost his wedding band in 2015 after tying it through his shoelaces and then leaving his trainers unattended.

Katie Boulter thought she had it that time. She really went for that inside-out forehand and it looks like it pinches the line, but Boulter is left looking up at the sky as 'out' is called.

And she won't get another chance. Carol Young Suh Lee gets herself on the board. That was a monster game.

A long forehand by Katie Boulter takes us to a sixth deuce.

But Carol Young Suh Lee replies with a wide forehand. Another break point for the Briton.

Katie Boulter shakes a clenched fist towards her team after she flicks a forehand into the corner, well out of Carol Young Suh Lee's reach.

She goes long on the next point, but another forehand winner hands her break point number three in this game.