Naomi Broady
Former British player on BBC Radio 5 Sports Extra 2

It felt like an important few minutes that. Alexander Zverev needed to step on it here...

Alexander Zverev responds to the double fault in style, pinging down a wide serve which is returned into the net and following it with an ace out wide.

Jakub Mensik looks crestfallen.

Alexander Zverev toys with the Czech. A backhand drop shot is chased down by Jakub Mensik, who plays his forehand cross-court, but as he tries to cover the down-the-line winner, Zverev plays the ball right back to where he was. 30-0.

But from 40-0, he's pegged back to 40-30 and then double faults for deuce.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Sports Extra 2 and BBC Sounds

These are indicators. Alexander Zverev is on the front front from the previous game. It seems like he is growing in confidence with winning the first set.

Image source, EPA

Once again, Jakub Mensik turns to the drop shot. Alexander Zverev is wise to it and pings a forehand tight across the net at a hideous angle and although Mensik scrambles to recover it, the German is in place to bury a backhand winner.

Momentum has well and truly swung in the German's favour.

Oh, Alexander Zverev's forehand is starting to purr.

Jakub Mensik comes on quite a tentative approach at 15-30 and Zverev whips a cross-court forehand winner around him. Two break points.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Sports Extra 2 and BBC Sounds

Alexander Zverev is sometimes so adamant from the other end of the court that he has clipped the line. It is so excessive, and he starts the conversation, then there is a battle within.

Image source, Getty Images

Alexander Zverev finds a couple of fizzing forehand winners which kiss the extremities of the court to race into a 40-0 lead.

A double fault blots his copybook, going too big on a second serve, but he recovers with a booming serve onto Jakub Mensik's backhand. The Czech returns it into court but Zverev's backhand is too strong.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Sports Extra 2 and BBC Sounds

For both players, the serve is the structure to their game. It is the pole that holds the tent up. There is a bit more fragility from Jakub Mensik behind that serve.

Image source, Getty Images

Another double fault for Jakub Mensik - his fourth of the match. 15-all.

He completes the hold to 30 with forehand winner at the net off a T-serve but those double faults are a concern.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Sports Extra 2 and BBC Sounds

When those break points arrived for Jakub Mensik, it was so quick. Perhaps not securing one of those rattled him.

Jakub Mensik saves one set point, coming into the net sharply to attack a flighted drop shot, and sees off a second after driving Alexander Zverev back behind the baseline.

However, Zverev seals the set with an ace down the T.

Three break points saved. One from one converted. Dominant in the big moments.

A big first serve which Jakub Mensik can only return into the net is sandwiched between two inside-out forehand winners.

Three set points for second seed Alexander Zverev.

Naomi Broady
Former British player on BBC Radio 5 Sports Extra 2

The first serve percentage is down to 50% for Jakub Mensik right now, which is pretty low.

It felt like it was a long time coming - there was relentless pressure from Alexander Zverev.

Alexander Zverev is quickly onto an over-telegraphed drop shot, whips a cross-court forehand reply and punches his fist as Jakub Mensik plants the ball in the net.

The German saved three break points in game eight, remember. Now he's serving for the set.

Image source, Getty Images

A messy service game from Jakub Mensik, with a couple of double faults leaving him 0-15 and 15-30 down.

He levels the game at 30-all but Zverev winds up a huge cross-court backhand which leaves the Czech rooted to the spot. Uh oh.

Image source, Getty Images

A couple of aces - one down the T with Jakub Mensik flailing for a backhand, the other out wide - help Alexander Zverev hold to 15.

But he looks a little off-colour in the lengthy baseline exchanges, lacking his usual depth and not quite finding the angles in the one point he dropped.

Jakub Mensik rattles through his latest hold.

Alexander Zverev will serve to stay in the first set.

Naomi Broady
Former British player on BBC Radio 5 Sports Extra 2

Absolutely massive. The first real test of serve. That was a huge opportunity for Jakub Mensik.

Image source, Getty Images

Opportunity missed! Alexander Zverev goes for the kill with a backhand on the approach but an unhelpful net chord allows the ball to sit up for Jakub Mensik, who charges in... and plants his forehand in the net. The German was exposed there.

Zverev completes the hold with a drop shot which Mensik can only return wide.

Three break points saved in that game.