Ben Shelton is looking to become the first American to reach the men's singles final in Melbourne since Andre Agassi back in 2003.

He's got a lot of work to do if he's to stop that unwanted run for the United States.

The first thing is to address those unforced errors. That's 32 now. Sinner, meanwhile, has 13.

The ball hits the net cord off Ben Shelton's forehand and it pops up nicely for Jannik Sinner to blast past his American opponent. An early lead for the defending champion.

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

The hitting from Jannik Sinner's end of the court is ferocious.

It is amazing how he can be inside the court and still strike the ball with thunderous timing.

Ben Shelton miscues his forehand and the ball loops high and wide.

A chance for Jannik Sinner to get the early break in this second set.

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Jannik Sinner goes wide, but Ben Shelton can't get the hold over and done with as his drop shot falls short of the net. Deuce.

No messing about from Ben Shelton, who goes big with a couple of aces to get him back up and running.

After pulling off a huge forehand winner he looks to his coaching pod and almost seems to be asking why he couldn't do that during his two set points in the first set.

But he'll have more questions to answer now. A long forehand brings up deuce.

Just the one. Ben Shelton pushes another forehand wide and Jannik Sinner, after saving two set points, claws his way back from the brink before steamrolling his way through the tie-break.

That's just what world number ones do, I suppose.

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Ben Shelton fires wide and hands Jannik Sinner four set points.

How many will he need?

Ben Shelton gets on the tie-break scoreboard as Jannik Sinner plants into the net. And again! 5-2.

Missing those set point seems to have really dented Ben Shelton's confidence as Jannik Sinner races to a 5-0 lead in the tie-break.

A long way back for the American now.

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

That was huge for Jannik Sinner.

I don't know why anybody is walking out of the stadium right now! They must be desperate to go to the toilet.

You don't want to miss a tie-break in this one.

Oh dear. After going long, Ben Shelton has the next point in his grasp as Jannik Sinner sprints the wrong way but the American fires wide. A bad miss, that. 2-0.

How big will that be? Ben Shelton had two set points, but it's Jannik Sinner who eventually pulls through.

He breaks back to force a tie-break.

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Back and forth we go. Jannik Sinner goes long before Ben Shelton gifts him another break point with a sloppy hit into the net.

How quickly things can change. Another opportunity missed from Ben Shelton and now it's Jannik Sinner's chance to break back.

Ben Shelton brings up another set point with a brilliantly-placed drop shot.

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Nope. A 20-shot rally goes the way of Jannik Sinner as Ben Shelton finds the net.

Ben Shelton sends his second serve into the body of Jannik Sinner, who can only launch the ball into the net.

Can Shelton take the first set at the first time of asking?

Ben Shelton knows this is a huge opportunity and he's attacking it with all his might, winning the first point by lashing the ball cross-court and out of Jannik Sinner's reach.

The American's attempt at the serve-volley doesn't come off, but he's let off the hook for now as Sinner fires long despite reaching Shelton's drop shot easily. 30-30.

An impressive return from Ben Shelton on Jannik Sinner's first serve sets him up well and the 21st seed controls the point before a dash and grab at the net clinches the break.

If he can hold serve here, that would be a massive win against the defending champion.

Image source, Reuters