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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.

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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.

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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.

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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.

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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.

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

When Alexander Zverev has had to face break points he is landing 80% plus of first serves.

I love to see Mensik getting in the view of Zverev and it was a quality second serve pace.

Disappointing from Jakub Mensik. He has another look at Alexander Zverev's second serve but punts his return into the middle of the court and then shanks a forehand long.

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Third time lucky for Jakub Mensik? He puts a bit of extra welly behind a cross-court backhand to leave Alexander Zverev scrambling and the German's reply sails long.

A good serve out wide saves the first break point for Alexander Zverev.

Then, he gets on top of the baseline in a lengthy exchange and overpowers Jakub Mensik with his forehand.

Alexander Zverev opens his service game with an ace out wide but hits a couple of forehand long under pressure from Jakub Mensik's deep hitting.

Trailing 15-30, the German comes into the net but Mensik slides across the baseline and passes him with a backhand.

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

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I am kind of looking at whether Jakub Mensik is talking to himself. The dialogue would be: 'I am not serving great, but I am still in the first set.' It was a much cleaner game on serve to hold from Mensik.

Another shake of the head from Alexander Zverev as he slides into a drop shot on the second bounce. It's an effective weapon from Jakub Mensik. 30-15.

He completes the hold to 30 after getting a second serve to rise into Zverev's body, cramping him for room.

That's his first service game that hasn't gone to deuce.