From being on the brink of losing the second set to drawing level with a hold to 15.

It feels like the momentum is on Aryna Sabalenka's side again.

What has McCartney Kessler got in response?

Emily Salley
BBC Sport at Wimbledon

Image source, Getty Images

That was probably tighter than Jannik Sinner would have hoped for, but he avoids falling a set down early doors like he did in his first round match against Miomir Kecmanovic.

The Italian turns to his team, shakes his fist and then struts back to his chair, looking confident.

Amy Lofthouse
BBC Sport at Wimbledon

That Sabalenka return was hit fast and hard and for all the world looked like it was going long. Kessler didn’t even move to return it.

This next service game could be interesting for Sabalenka. She’s cranked the noise up a level to try and spur herself on, but she’ll need to hold relatively sharpish to keep Kessler at bay.

Image source, PA Media

That's magnificent from Aryna Sabalenka as a powerful backhand return winner seals the break back after dominating the previous point in a rally.

Kessler is made to pay for not taking those two set points.

Jannik Sinner closes out the opening set at the first opportunity.

Coming on the approach, he hammers a forehand deep into the corner on Nuno Borges backhand and although the 29-year-old puts in a good scramble, all he can do is get his frame on it.

Borges was hanging in a little at the back end of the tie-break. How will he respond?

Huge second serve from Jannik Sinner to tee up set point.

Jannik Sinner earns the mini-break with a deep return which Nuno Borges returns into the net.

His eyes light up as the court opens up for a backhand pass for set point but his shot clips the net cord and pings into the tramlines. But, the Italian is two points away from taking the first set.

McCartney Kessler chooses the right time to come into the net and force Aryna Sabalenka into a mistake.

She can't take her second set point however, as she overcooks a forehand.

Jannik Sinner eases through two points.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live

Image source, Getty Images

Nuno Borges has been playing really well.

He is serving at 77% first serves. Don't get me wrong, they aren't the hardest serves in the world but they are big and he is hitting the ball cleanly.

This is a very even match - and it isn't surprising that we are in a tie-breaker.

Too good from Aryna Sabalenka, who slams a return over which McCartney Kessler can do little about.

The world number one reacts with a bellowing "come on".

Kessler reacts superbly, getting to game point but can't get over the line as a forehand spoons wide.

129mph ace from Nuno Borges - lovely.

Jannik Sinner immediately surrenders his advantage with a loose backhand but keeps his nose in front with an inside-out forehand.

Jannik Sinner offers a clenched fist of celebration - a rare show of emotion - as he lands a backhand pass for an early mini-break.

Not a great decision to follow a mis-hit into the net from Nuno Borges, the ball sitting up nicely for Sinner.

Aryna Sabalenka puts too much into a powerful forehand which sails long, drawing oohs from the crowd.

McCartney Kessler's backhand winner then sends the game to deuce.

Sabalenka reacts well by winning an entertaining rally before a strong first serve seals the hold.

Jannik Sinner trails 0-15 but it's the briefest of scares. He rattles through the next four points to hold.

Harry Poole
BBC Sport at Wimbledon

Sadly we saw the end of Dan Evans' playing career after his earlier defeat alongside Henry Searle, but we have plenty more British players in doubles action today - quite the treat for those without tickets to the main show courts.

I've nipped over to court eight, where three of the four players in action are competing at their home Grand Slam.

Ten years after his run from qualifying to a second-round meeting with the great Roger Federer on Centre Court, Marcus Willis, playing alongside David Stevenson, is up against Joe Salisbury, a six-time major winner in doubles competitions, and Uruguayan Ariel Behar.

This is another well-attended match, with viewing space at a premium, and the crowd which has gathered here do at least have the comfort of knowing at least one British player will be celebrating at the end.

The first set goes the way of Salisbury and Behar.

Oh, that's quite lovely from Nuno Borges. Coming on the approach, he winds up with a flat racquet face before switching angle at the last second to ping a cross-court forehand winner. Cool as you like. Jannik Sinner was completely wrong-footed.

For a second time, Sinner will have to serve to stay in the set, but having only dropped two points all match, a tie-break feels inevitable.

Chris Bradnam
BBC Sport commentator at Wimbledon

You are really now starting to hear from Kessler.

The crowd wanted a match after the quality of the first set and they are getting one.

With help of her brother, you can see the tactical switches. It is a real turnaround now from Kessler.

It is getting better and better.

Tom Corrie
Tennis expert on BBC Radio 5 Live

Aryna Sabalenka had the highest performance rating, which takes into account basically everything that happens in a match, in round one of the women's singles with 9.44. It was basically near-perfect tennis from her.

That metric isn't to do with winning or losing, it is to do with everything you're doing in a match such as how you are moving or hitting the ball.

She has actually come out the blocks today and topped it with a 9.49 rating. Her score has dropped a little bit in this second set, though.