Jannik Sinner shakes a clenched fist after his soft hands dink over a deft volley. An ace nudges him ahead. 5-4.

The chalk flies up as Alexander Zverev hits a 139mph serve down the T. Pinpoint accuracy.

Marion Bartoli
Former Wimbledon champion on BBC Radio 5 Live

Image source, PA Media

Sinner has been responding beautifully to the pressure that Zverev has been trying to put on him.

Alexander Zverev is left shrugging his shoulders after another Jannik Sinner serve finds the chalk. He can only skew the return wide.

An ace out wide pulls Jannik Sinner level at 2-2.

Jannik Sinner sends Alexander Zverev scrambling on the first point, but the Italian nearly does the splits on the next one as he finds himself on the end of a fiery forehand by the 6ft 6in German.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 Live

In tie-breaks this tournament, Zverev has won six out of seven, Sinner four out of five. Over the course of the season, however, Sinner has won a higher percentage of the tie-breaks he has played.

Jonathan Jurejko
BBC Sport tennis news reporter at Wimbledon

Zverev has often been accused of playing too passively in the biggest matches against better opponents, but he has come out more attacking against Sinner.

Something had to change if Zverev was going to stand any chance of ending his miserable run of nine straight defeats.

The German second seed has certainly done that - let's find out if it will be enough to finally win a first set against Sinner after losing the past 14.

We're going to a tie-break. It was inevitable, wasn't it?

Jannik Sinner lands a lovely volley on the approach before Alexander Zverev smashes down an overhead and picks out an ace down the T.

Another big serve is followed by a backhand winner that had Sinner wrongfooted.

Marion Bartoli
Former Wimbledon champion on BBC Radio 5 Live

Image source, Getty Images

It will be interesting to see how much of this new mindset Zverev can maintain.

Good net play there from Jannik Sinner as he taps over a volley after failing to fool Alexander Zverev with the drop shot.

The second seed fires wide before Sinner grabs the love hold with an ace - his fifth of the match.

Back to you, Zverev. Can he force a tie-break?

Andre Agassi
Former Wimbledon champion on BBC One

You have to come out here and shake the cage a little bit. A lot easier to do that as a French Open champion like Zverev. He is looser than I would expect him to be beforehand. He is letting the forehand go.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live

This is new territory for Zverev [being so aggressive].

Sinner's team will be saying 'don't mind if he hits a few winners, he won't keep it up', whereas Zverev's team will be believing he can keep it up.

That was seriously impressive from Alexander Zverev. He was on the defence there but he puts an abrupt end to the rally with a lassoed forehand winner down the line.

Jannik Sinner gets lucky with return that trickles over the net, but that's about all the fortune he has as Zverev charges to the hold.

Engrossed.

Image source, PA Media

Jannik Sinner finds a way through to pile the pressure back on Alexander Zverev.

He moves to one game away from the opening set.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live

Margins are ridiculously small.

One forehand from Zverev on the Sinner serve and one forehand from Sinner on the Zverev serve. Shows you you don't get many chances.

Alexander Zverev had the chance to apply some pressure on Jannik Sinner's serve, but he flicks the ball wide. Sinner was never getting to that had he made the shot.

But he'll get another look as the Italian nets. 30-30.