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LIVE: Defending champion Jannik Sinner wins first set 7-5 against Jan-Lennard Struff on Court One
LIVE: Jessica Pegula v Coco Gauff on Centre Court
Once Pegula v Gauff finishes, men's second seed Alexander Zverev will resume fourth-round match with two-set lead over Jiri Lehecka
GB's Gordon Reid loses 6-3 6-1 to defending champion Tokito Oda in men's wheelchair singles first round; Alfie Hewett playing now on court three
Experience Centre Court Interactive with SIGNALS - click into real-time data analysis, quizzes and fan interaction
Pegula 5-3 Gauff*
Jessica Pegula is closing in on this first set.
She has been the more controlled of the two Americans thus far, perhaps that one oddly passive service game aside.
Coco Gauff gave herself a chance at 15-30 but Pegula remained focused and calmly secured the hold.
Sinner 7-5 1-1 Struff*
Image source, Getty ImagesJannik Sinner eases through a hold to 15, sealing it with an ace down the T.
Emily Salley
BBC Sport at Wimbledon
Uh oh. Right in the middle of a lengthy rally, a stray ball rolls onto the court and stops Jan-Lennard Struff in his tracks.
"Let," says the umpire. "Replay the point".
That might just have worked in the German's favour, helping him fend off the break point and hold.
*Sinner 7-5 0-1 Struff
Jan-Lennard Struff comes up with a couple of first serves to navigate deuce. He's had a huge stroke of fortune at the start of this second set.
*Pegula 4-3 Gauff
Harry Poole
BBC Sport at Wimbledon
As I was saying...
Best get ourselves settled in for a bit of a rollercoaster here, I reckon.
*Pegula 4-3 Gauff
What did Harry just say about Coco Gauff putting her fans through the wringer?
No sooner has she broken back, she hands the advantage right back to Jessica Pegula.
A double-fault is a fitting way for that game to end. Two breaks of serve for Pegula so far but Gauff will feel they have been far more about her serving than anything special from her fellow American.
Image source, PA MediaSinner 7-5 0-0 Struff*
Ooooh a let-off for Jan-Lennard Struff as a ball falls out of his pocket midway through a lengthy baseline exchange. He was firmly on the back foot in that rally.
They replay the point and Struff comes up with a big serve which Jannik Sinner returns wide.
Sinner 7-5 0-0 Struff*
Double fault and an ace down the T to open the second set from Jan-Lennard Struff. 15-all.
Jannik Sinner reads a smash, forces Struff to attempt a second, and the German puts his overhead into the tramlines.
Struff takes a big deep breath and finds a hefty wide serve. 30-all.
And then, he messes up a serve and volley, unable to ping Sinner's low return back over the net.
Pegula 3-3 Gauff*
Harry Poole
BBC Sport at Wimbledon
Coco Gauff doesn't half put her supporters through it.
The 22-year-old doesn't tend to hide her emotions, and her frustration was clear after she made that a horrible miss at the net to gasps from the crowd. It looked like a sure thing.
It's been an impressive response since, however. She hints at her growing confidence with that big return to break back.
Cheers on Centre Court as it appears Gauff has arrived in this contest.
Pegula 3-3 Gauff*
Just like that, Coco Gauff breaks back.
Jessica Pegula looked off it that whole game and Gauff took full advantage.
The seventh seed meant business while Pegula's backhand into the net down 0-40 looked very weary.
We're only six games in!
Image source, Getty ImagesEmily Salley
BBC Sport at Wimbledon
Jannik Sinner looks up to his team and gives a slight shake of his racquet after wrapping up the opener.
He hasn't done anything spectacular yet, but he hasn't needed to and the Italian strikes just at the right moment.
Sinner 7-5 0-0 Struff*
John McEnroe
Three-time Wimbledon singles champion on BBC Two
Jannik Sinner loves that serve on the advantage court out wide. It is so tough to handle for any opponent.
This is exactly the match he would've expected to be playing. He just needed to keep his cool, wait for his opportunity and jump on it - and he did that.
What does that do to Jan-Lennard Struff, having played all that tennis? Will he let down a little bit or will he keep up this effort? It won't be easy for him.
*Pegula 3-2 Gauff
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live
These two decided that doubles wouldn't be a part of their major tournaments. I think that was a good call from them. It's just a part of tennis, playing your friend.
Sinner 7-5 0-0 Struff*
Jan-Lennard Struff drags his backhand wide to hand Jannik Sinner the opening set.
Barely 15 minutes ago, the Italian was down 5-4 and coming into a key service game off the back of three sketchy holds. But he came through with a hold to love and then made the crucial break.
How Struff must be ruing those three wasted deuces.
Image source, Getty Images*Pegula 3-2 Gauff
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live
I like the play from Gauff. Especially when your forehand feels horrible, you want to play as close to the net as possible.
*Pegula 3-2 Gauff
A smidgen of pressure on Coco Gauff as she puts an overhead volley into the net to go down 15-30 on serve.
She responds well, though, a couple big serves get her out of trouble before Jessica Pegula hits tamely into the net.
Pegula stays just the solitary break up.
*Sinner 6-5 Struff
Jan-Lennard Struff is showing no signs of fatigue despite spending more than 14 hours on court, charging from one side of the baseline to the other to hunt down a Jannik Sinner drive volley. Alas, his skied reply lands wide. 30-0.
He pulls one point back but with an ace out wide, Sinner has two set points.
Pegula 3-1 Gauff*
Image source, Getty ImagesJessica Pegula is playing with real confidence here.
Another comfortable hold, the highlight of which is another fine passing shot, fired down the line on the backhand.
*Sinner 6-5 Struff
Ace. Ace. Two break points saved in the blink of an eye.
But then Jannik Sinner steps into a second serve, taking the ball on the baseline with both feet off the ground, and wipes a cross-court forehand winner.
Huge.
Sinner 5-5 Struff*
Greg Rusedski
Former British number one on BBC Radio 5 Live
It seems like all of a sudden, Sinner is reading the serve of Struff. This is where you separate the boys from the men, I expect Sinner to lift his game right now.
