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Superb from Coco Gauff to bring up two break points.

Her drop shot isn't brilliant but she stretches to reach Jessica Pegula's return and produces an excellent lob volley to win the point.

Just one break point is required as Pegula's forehand skews wide.

It's been a high-wire act from Gauff for much of this match but now she leads for the very first time.

We've been asking for your questions during Wimbledon and Pete in Kent asked:

How is it determined whose name is first or top on the scoreboard?

We put the question to the All England Club, who said:

It is the player who appears first in the draw - so, for example, Jannik Sinner will also be at the top as he is on the first line of the drawsheet, while Alexander Zverev will always be on the bottom as he is on the last line of the drawsheet.

Emily Salley
BBC Sport at Wimbledon

Jannik Sinner might not be playing at his very best, but he looks calm and composed as he struts back to his chair. He's upped his level once again at the right moments.

Both players are taking a bit of time off court before the start of the third set - probably to get a bit of relief from the heat.

Andrew Castle
BBC Sport tennis commentator on BBC Two

Well that was a magnificent tie-break from the defending champion!

He has the first two sets, but Jan Lennard-Struff has come back from two sets down at Wimbledon plenty of times.

This looks to be a very high mountain to climb though.

Jan-Lennard Struff takes a couple of paces in to attack a second serve but his deep reply lands inches long.

Defending champion Jannik Sinner leads by two sets to love. His serve came up trumps at the back end of the set.

But don't count Struff out just yet - three of his four matches at the tournament so far have gone to five sets. He's a fighter.

Image source, PA Media

Booming forehand return from Jessica Pegula as she targets Coco Gauff's second serve.

That puts her up 15-30 but Gauff responds with another ace.

Pegula brings up break point with a superb, dipping shot as she spots Gauff coming into the net.

The fourth seed can't convert, though, and - eventually - Gauff escapes with the hold.

Yup, you've guessed it. A big first serve from Jannik Sinner isn't returned into play.

Jan Lennard-Struff rattles through two quick points of his own.

Greg Rusedski
Former British number one on BBC Radio 5 Live

Sinner is serving magnificently, that's what is keeping him out of trouble.

More first serves from Jannik Sinner, including an ace out wide. He's two points away from a two-set lead.

Greg Rusedski
Former British number one on BBC Radio 5 Live

It's been a very unusual from Jannik Sinner today. A lot of unforced errors from the back of the court, weak forehand.

He doesn't look like the supreme force Jannik Sinner that we're used to

One thing that has been impressive from him today is his service game.

Jan-Lennard Struff plants a routine backhand into the net. Jannik Sinner offers a shake of the racquet. He has the mini-break.

Struff stays in touch with some sharp net play.

Jannik Sinner responds with two mighty first serves of his own. Jan-Lennard Struff gets a racquet to both but can't put his returns in court.

Jessica Pegula brushes off the disappointment of dropping that second set with a comfortable hold to start the third.

Harry Poole
BBC Sport at Wimbledon

Jessica Pegula will be kicking herself. Having had the chances to put herself on track for a straight-set win here, she has gifted Coco Gauff a route back into this match.

Gauff skips in celebration and clenches her fist as she strides to her chair, while Pegula has he head bowed as she walks over from the baseline. Now it really is anyone's match.

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Jan-Lennard Struff opens with an ace.

Jannik Sinner holds to 30 with an ace down the T.

These two exchanged breaks in games three and four of the second set and both failed to convert break points later on - Jan-Lennard Struff missing out on set point. There's only one way to settle this: tie-break!

Image source, PA Media

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live

This is why Coco Gauff has won two majors. She doesn't mind winning ugly.

Andrew Castle
BBC Sport tennis commentator on BBC Two

Both players are in the trenches in this one, aren't they? It has been a kind of old-school match.

Jan-Lennard Struff has come out here and used his enormous experience. He knew full well that he didn't want this to be a pretty looking tennis match because he would lose it. He is just taking the ball and hammering whenever he can. Jannik Sinner, on the other hand, is doing what he can to just keep his nose in front.

There is one great player on this court and the other player is just an unbelievably good workman. It is quite the match-up.

We're going the distance, folks - and you were warned!

Coco Gauff battles back from 0-30 down and hammers an ace down the middle to take the second set.

Things become so much simpler for her when that serve is in even halfway decent order.

Jessica Pegula will rue not taking her chances early in that second set.

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