Piers Newbery
BBC Sport at Flushing Meadows

Denis Shapovalov might have captured most of the attention among the new names breaking through at this year's US Open, but fellow teenager Andrey Rublev has outdone the Canadian - and the Russian shows no sign of stopping.

The 19-year-old clenches his fist and walks purposefully back to his chair after clinching the first set against eighth seed David Goffin. Face sensibly smeared in sunblock on a toasty Louis Armstrong Stadium, Rublev is two sets from becoming the youngest quarter-finalist since Andy Roddick in 2001.

Image source, Reuters

Dolgopolov has a go at showboating, with a pirouetting mid-air backhand above his head. It doesn't really work as it flies cross-court and outside the lines, but it looked pretty.

No bother, though. He still holds.

Those 49 wins (to date) include two titles, in 2010 and 2013.

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Nadal's body serving is proving fruitful as he takes the first two points.

Make that three points, as Dolgopolov smacks into the net.

Nadal holds to love with an ace. That'll do.

Image source, EPA

Alexandr Dolgopolov lands a marvellous half-volley on his way to a quick love hold.

That's much better from the Ukrainian.

Boom! A big ol' overhead smash gives Nadal a 30-0.

At the other end, Dolgopolov appears to be talking to himself - Andy Murray style. I've missed that this year.

Nadal ends up holding to 15, finishing off with a stretching volley.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Mostly Alexandr needs to just pick it up with attitude, not necessarily his game. Put a little bit more air into his game, some arrogance into his shots. He needs to make shots that dent Nadal.

Image source, AFP

Dolgopolov takes the advantage with a lovely low backhand winner which just scales the net, and then Nadal returns long.

A big hold.

Alexandr Dolgopolov is raring to go for the second set, but as usual Rafael Nadal takes his time to get in position. He gobbles up one of those awful energy gel things and slowly takes his place on court.

The Ukrainian world number 64 lands an ace for 40-30 but nets the next point and we're on to deuce.

Nadal whips out a frankly ridiculous whipped forehand winner to earn a break point. He can't take the opportunity this time though. He's found the net. We continue...

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

I think the ball is bouncing two feet higher [on Arthur Ashe] than it normally would and that's right in the strike zone of Del Potro, Nadal and the clay-court players.

Nadal is a stickler for noticing tiny little things in his way. He's constantly surveying the court, looking for bits of paper, bits of trainer, bits of anything that might get in his way.

After disposing of the latest unidentified object, he brings up three set points.

One goes amiss, but on the second opportunity he comes up trumps with a big serve.

Easy.

Image source, Rex Features

Image source, Getty Images

Early stages on Louis Armstrong where world number nine David Goffin (above) is facing Russian teenager Andrey Rublev.

Rublev has disposed of Grigor Dimitrov and Aljaz Bedene on his way to the fourth round and the 19-year-old leads 3-2 on serve in the first set.

The winner plays either Nadal or Dolgopolov.

Image source, Getty Images

David Law
Radio 5 live sports extra commentator at Flushing Meadows

This is typical of the very top players. 'You'e a bit down in the dumps because you didn't break - I'm going to break you now.'

Nadal starts to turn the screw on Dolgopolov's serve again. It's 0-30.

Two break points follow, when Rafa outsmarts his opponent at the net. That was cheeky.

One break point is saved by a nice straight forehand winner by the Ukrainian, but Nadal pulls out the big guns and backhands cross-court to take the game.

The world number one will serve for the first set and we're less than half an hour in.

Image source, EPA

After toing and froing on deuce, Nadal finally holds when Dolgopolov screws up a dropshot.

Another break point for Dolgopolov. He has the advantage.

But not for long. He plants a forehand over the line. Back to deuce.

Nadal then overshoots the baseline...or has he? He challenges and he's right! We replay the point. A great call!

Image source, Reuters

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Dolgopolov has to be thinking he has a chance. This is a lesson for Nadal - every time he places one of those spinny balls into the centre of the court, he's going to get burned.

At 15-15, the pair engage in a baseline war and Nadal wins the point with a brilliant, thumping backhand winner into the corner.

Dolgopolov won't be denied, though. He lands his own backhand winner to level.

And now he's gifted a break point when Nadal double faults.

The Spaniard saves it. We go to deuce.

Image source, AFP

Dolgopolov gets his house in order on serve. He's 40-0 up.

A maiden ace sees him hold without dropping a point.

Image source, Getty Images

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Boy, is Nadal covering the net well. John McEnroe has been saying Nadal is the best volleyer on tour. Dolgopolov is looking a little grumbly as he looks up at the sun.