This should be a really good game - Tiafoe has a lot of talent, and took Federer all the way in New York. Hopefully I'll have pictures of this when Federer is done.

As for us, I'll be back in 30 or so for the snooker - it's O'Sullivan v Fu, so you should definitely join me for that.

So there we go. The crowd cheer Tiafoe as he walks off, while Del Potro will play Karen Khachanov next.

A blazing forehand from Tiafoe gives him 15-0 and is followed by a serve that's returned into the net. But out of nowhere, Del Potro smites a forehand, inside-out, from the middle of the court to the backhand corner - the crowd gasp - and a fine return makes it 30-all. Then a backhand from Del Potro forces an error ... match point ... and then Tiafoe goes wide with a forehand! Del Potro lets out a roar because that was his first match in Melbourne for four years and because that was not an easy night at all - Tiafoe is a talent, and has a temperament to match; he just isn't as good as Del Potro, but maybe one day.

Tiiafoe is hanging in there, hammering down an overhead at 30-15 to remind Del Potro that he needs to keep it real. So he does, a taxing serve down the middle returned into the net ... but then an accidental winner, hit on the return and via backhand, brings a bit of pressure; Del Potro handles it, pouncing on a short return to set up a forehand cross-court winner. He's a game away.

Tiafoe does really well to maintain discipline and focus, holding to 15.

Tiafoe gets up 0-15, so Del Potro hammers down an ace. Tiafoe gets up 30-15, so Del Potro sends a serve out wide then cleans up with a forehand into the opposite corner - with the help of a net cord. Then another big serve, then an ace, and this is close to did.

At 30-15, Del Potro runs out into the tramlines to power a backhand winner down the line. He's looking better and better on that side, and Tiafoe then makes an error; break point and, let's be real, more or less match point. And there it is! Another driven backhand from Del Potro, this time cross-court, is too good. He needs to hold three service games for a place in round 2.

Del Potro holds to 15. Has he seen Tiafoe's hot streak away? I'd not be surprised to see a break in the next game.

Meanwhile, elsewhere...

A booming forehand from Del Potro gets him to 15-all, so Tiafoe responds with an ace, swinging out wide. But at 30-all Del Potro smacks a forehand down the line and then another cross-court with everyone expecting another down the line ... only for Tiafoe to crunch a pair of forehands to bring it back to deuce. Seconds later, he's back in front in the set, and this is a really good and fun match now.

At 30-0, Tiafoe powerstrokes a forehand down the line that bounces just in. He's really into this now, and another winner takes him to 30-all. But just when he looks to be on a streak, Del Potro eases through two points, and the half-chance disappears.

7 minutes 25 seconds after the last point, Tiafoe restarts, then at 15-0 has to adjust his shorts. They end up at 30-all, and Tiafoe might be bricking it but isn't - I really enjoy his temperament, he'll be delighted to learn. He gets to 40-30, but then a devilish slice from Delpo brings us to deuce. Oh ad that's gorgeous! At advantage, Tiafoe delivers a delectable lob! He's learning on the job here!

During change of ends, the umpire very reasonable advises Del Potro that he's taking too long between points. Del Potro doesn't like it, but so pleasant is the tone that he has no option but to relent, before Tiafoe disappears for a dump.

At 15-0, Tiafoe snaps a backhand return down the line, and then a net cord give him a glimmer. He apologises when Del Potro isn't looking, then celebrates it when he is - lovely stuff. And what's this! Another winner, and Tiafoe has two break points! Del Potro serves into the net, but still gets on top in the next rally and eventually the pressure tells, Tiafoe needlessly botching a forehand. He'll be regretting that now, because the serve that hurtles over the net is far too much ... but then Del Potro can't kill a fine cross-court pass, and Tiafoe charges into the net to finish the point. He looks in the next rally too, picking Del Potro's serve and returning deep, but the eventuating forehand clips the line and he can only respond with a racket edge. No more chances. A big serve, a slice causing the rear-most fibre of the ball to catch the line, and that's 2-0. Props to Tiafoe though, he had a really good shy at that.

Tiefoe gets to 40-15, whereupon a backhand drive from Del Potro - I know! - is followed by a delicate slice. And ... and ... oh dear! With Del Potro nowhere, Tiafoe over-slices an overhead, and must now face deuce. Del Potro then raises advantage, but Tiafoe digs out a really good forehand topspin pass - his racket speed is excellent. He then shows the other side of his game, gliding a backhand across the face of the net, wins the next point too, and Delpz will have to serve for it.

Elsewhere, Dominic Thiem, seeded 5, has beaten Pella 4, 4 and 4. Del Potro races through a love game, finishing with a high-kicking ace.

Tiafoe understands that to win this, he'll need to make it a physical match - Del Potro moves well for a man of his size, but that isn't the same as moving well - and sends him clomping about for 30-0. But an errant forehand makes it 30-15 and then at 40-15 decides they should exchange forehands for kicks; guess who wins! seconds later it's deuce. Tiefoe, though, is not short on confidence and whips a beautifully disguised drop-shot for game-point, finishing it off with a more gentle version of the same. This is really entertaining stuff.

What Del Potro has that not many have is the ability to speed the game up and suddenly rattle through games at the business end of a set. The difficulty, though, especially against Nadal, is that Nadal's topspin forehand plays right into his backhand, and since that wrist situation, he can really only respond with a slice, which doesn't cut it. Anyway, Tiafoe gets to 40-30 on his serve, then ballons a top-spin forehand; he's running out of chances in this set.

So, can Del Potro win this competition? His win over Federer in New York was one of the most uplifting sporting moments of the year, but he then fell foul of Nadal. If he's to succeed here, he'll probably need to beat Federer in the semi-final and probably need to beat Nadal in the final, which is annoying for him given that's not simply a factor of them being seeded 1 and 2. That's not easy to expect but not impossible to foresee. Anwyay, Tiafoe holds.

Tiafoe makes his first impression on the Delpo serve, forcing deuce before the inevitable happens.

Brilliant game from Del Potro, who breaks to love.