Emily 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.

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.

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.

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.

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.

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.

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.

Image source, Getty Images

Jessica 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.

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.

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.

Jannik Sinner pounds a forehand winner. 0-15.

Jan Lennard-Struff follows a serve into the net, tries to take Sinner's return out of the air - his racquet high up on his backhand - and puts the ball into the net. 0-30.

Sinner wallops a return. 0-40.

UH OH.

Coco Gauff is on the board.

After showing us example of her weaknesses early on, she shows the skill that helps her to overcome them here.

Jessica Pegula must have thought she'd hit a winner when she lasered a backhand return down the line but Gauff just about gets it, jabs her racquet down and somehow gets the ball cross-court, just over the net to win the point.

Image source, PA Media

John Lloyd
Former GB Davis Cup captain on BBC Two

Jan-Lennard Struff is way better than his ranking on grass. I don't understand why he hasn't done better at Wimbledon, to be honest, considering the game he has got.

He has had the tendency to serve double faults on big points in the past, but he seems to have corrected that so far in this tournament. I do think his whole mental attitude has changed recently, I think he sort of gets the game now at 36 years old.

Image source, Getty Images

A routine hold to love for Jannik Sinner, finding some first serves at last.

He looks up to his box and shakes his racquet with a look of determination.

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

Pegula was my pick to win, pre tournament. But, the way Naomi Osaka played the other day...

Harry Poole
BBC Sport at Wimbledon

Issues on serve - and especially her tendency to double-fault in key moments - has long been the biggest obstacle to progress for Coco Gauff.

Although a two-time major winner, that problem very much remains as we’ve just witnessed in the opening game.

There are groans in the crowd as she falters to lose serve from 40-0, followed by shouts of encouragement. That was absolutely not the start she needed here against top-ranked American Jessica Pegula.

Emily Salley
BBC Sport at Wimbledon

Jannik Sinner wastes no time in getting an ice towel wrapped around his neck as soon as he sits down.

The Italian has a tendency to struggle in the heat, so it will be interesting to see how he copes this afternoon with temperatures set to reach at least 30C.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live

Gauff is such an incredible athlete and competitor but we all have our weaknesses, we somehow have to work with them and around them.

Image source, Getty Images

Jessica Pegula holds with a minimum of fuss.

A lovely cross-court passing shot gets things started and a smart drop shot takes her to game point before Coco Gauff fires long.

At 15-all, Jan-Lennard Struff glides forward and plants a routine volley into the base of the net.

He responds with an ace and clenches his fist enthusiastically as Sinner sends a forehand long off a second serve.

Ace to hold. More fist pumping at the change of ends.