What a shot that is from Jannik Sinner, a powerful return of Marcos Giron's serve into the back corner.

All of a sudden, from 40-15, we're at deuce.

Jannik Sinner has used that dropshot from the back of the court to good effect in this match but this time it doesn't pay off as it falls on his side of the net for 30-15.

Marcos Giron wants to make Sinner serve out the set.

Back-to-back aces from Jannik Sinner bring up game point. He's hit six so far in this match.

His second serve is pretty tricky to deal with too as Marcos Giron can only send back a hopeful return which Sinner dispatches into the corner to take the hold.

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Almost a bit of a scare there for Marcos Giron but he takes the hold to keep himself in this set.

Jannik Sinner saw an opening at 30-30 but could not close out in the rallies and Giron came through.

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American 21st seed Ben Shelton is into the fourth round in Melbourne after overcoming Italian 16th seed Lorenzo Musetti in four sets.

Shelton won 6-3 3-6 6-4 7-6 (7-5) on the John Cain Arena.

Shelton, 22, will face France's Gael Monfils in the last-16 after the 38-year-old stunned American fourth seed Taylor Fritz earlier today.

Jannik Sinner once again gets himself out of trouble with an ace.

The Italian takes the hold after drawing the error from Marcos Giron then finds another ace to give himself some breathing space on the scoreboard.

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

There's a little more emotion than I am used to seeing from Marcos. Maybe it’s a sign of how uncomfortable it is playing against Jannik Sinner.

Marcos Giron is chuntering away to himself at the baseline after dumping his forehand into the net.

Jannik Sinner has lost just three points off his first serve and he finds his fourth ace of the match for 30-0.

But the American hangs in there and draws level at 30-30 then brings up a break point as Sinner goes for the drop shot but can only find the wrong side of the net.

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Got it.

Jannik Sinner takes his the break at the first opportunity.

Ah, Marcos Giron in trouble after making significant improvements in this second set.

Jannik Sinner just shows his class as he brings up two break points.

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

It just looks like Giron has warmed up into this second set.

The serve is starting to pick up velocity and in rally mode he is hitting with a bit more authority.

Jannik Sinner is a long way back but takes the pace off the ball and floats down the drop shot unexpectedly. Marcos Giron is left scrambling.

Sinner has the game wrapped up a couple of minutes later after an ace and an overhead smash volley.

These service games are looking more and more assured from Marcos Giron.

When he can nail a first serve, he's in business. He finds a few to take the hold to love.

Good play from Jannik Sinner, that, to take the hold to 15.

Marcos Giron doesn't do much wrong apart from a slightly weak backhand which Sinner takes full advantage of, advancing into the net and sending a passing shot down the line.

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A better start for Marcos Giron in the second set as he takes the hold to 15 with some really good serving.

Whether he can make inroads on the Jannik Sinner serve is another matter.

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Over on the Margaret Court Arena, Italian fourth seed Jasmine Paolini has just taken the first set 6-2 against Ukrainian 28th seed Elina Svitolina.

Paolini, who reached the final of the French Open and Wimbledon last year, is looking to match her best-ever performance in Melbourne after reaching the fourth round last year.

Gael Monfils, who beat American fourth seed Taylor Fritz earlier today on the same court, is the husband of Svitolina and is watching on with a thoughtful expression.

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

The Italian feels like he is going down the slopes, great balance, helps control the racquet face but maybe got a bit lucky.

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Jannik Sinner takes the opening set after earning the single break early on.

A huge crunching ace out wide is impossible for Marcos Giron to reach and that's the first set on the board for the defending champion.

First set point missed with another unforced error.

Jannik Sinner will get a second bite of the cherry after Marcos Giron is caught off-guard by the Italian's forehand.

Break point saved with a crunching serve.

Then a brilliant shot gives Jannik Sinner set point as he digs one out from miles behind the baseline at full stretch and places it far out of Marcos Giron's reach.