Shapovalov has plenty of support in the stands.

The crowd get excited as the Canadian moves to 0-30, and that only grows following a double fault by Khachanov which sets up three break points.

Khachanov goes long in attempting to return a big forehand, giving control of the fourth set to Shapovalov.

Briton Joe Salisbury and American Rajeev Ram are in the semi-finals of the men's doubles after a straight sets victory over Colombian duo Juan Sebastian Cabal and Robert Farah.

Salisbury hit the winning point as he and Ram wrapped up the win in two hours and 11 minutes courtesy of a third-set tie-break and the pair will now face top seeds Nikola Mektic and Mate Pavic of Croatia in the last four.

Salisbury is not quite done for the day yet, though. He has a mixed doubles match against Austrian Oliver Marach and Lyudmyla Kichenok of Ukraine with partner Harriet Dart later on.

The groans are increasing from Novak Djokovic as he flirts with the baseline on a series of deep groundstokes, before Marton Fucsovics punches long. Deuce.

Marton Fucsovics isn't going away just yet, edging to 15-30 and forcing Novak Djokovic to bring his best with a series of delightful groundstrokes from the baseline that eventually swat prove too hot for the Hungarian to get strings to. But then a miscued backhand from Djokovic... break back point!

Clinical serving from world number 12 Shapovalov.

He's won 100% of his first serve points after two games in this fourth set. The Canadian leads 2-1 after his latest hold.

Sonia Oxley
BBC Sport at Wimbledon

Even the used tennis balls are subject to Covid restrictions this year.

Normally they come straight from the court before being sold to the public for fans' chance to get their hands on a bit of yellow fluff hit by Roger Federer et al.

But this time they have to be put in quarantine for "a few days".

So by my reckoning, the ones on sale today could be ones hit by Andy Murray last week (maybe).

Image source, BBC Sport

Woah. That is tugged away for six by Marton Fucsovics, probably coming down in a neighbour's garden too as he hooks a forehand into the SW19 sky. But it's a brief blemish on the Hungarian's card as he dusts himself down to hold.

Khachanov saved a break point before sealing the third set with this point...

This match is a joy to watch on Court One.

Shapovalov volleys at the net from a Khachanov tweener after a breathless exchange, but the Russian composes himself to close in on the hold of serve.

Shapovalov forces deuce, but that's as good as it gets for the Canadian on this occasion.

Novak Djokovic makes a forehand winner look remarkably casual and complements it with a couple of volleyed points on his way to 40-0 before holding to love.

LordGreystoke: Karen telling Shapovalov in no uncertain terms "Khach me if you can...."

Very nice from Marton Fucsovics, a superbly engineered point that he eventually takes with a drop volley. It's good enough for some applause from Novak Djokovic. And the Hungarian holds with an ace.

Big, big forehand from Novak Djokovic but there's too much on that and it drifts long. Deuce.

Uh oh. A double fault just when Marton Fucsovics needed it least. It hands Novak Djokovic break point and chance for a 3-0 in the third.

He's lost the last two sets, but the young Canadian Shapovalov isn't letting his head drop.

A perfect sliced drop shot sets him on his way to a hold at the start of the fourth.

Here's how Novak Djokovic edged into a two-set lead...

The Hungarian chanters away to his box, frustrated by a forehand that drifts wide as the break point goes begging, and Novak Djokovic edges in front in the eighth minute of this service game... and eventually holds after a mammoth exchange! He roars in celebration.

Challenge from Novak Djokovic, and he's on the money with a serve that kisses the chalk. But then the top seed coaxes wide and Marton Fucsovics has another chance to break.

Khachanov appears to tighten up at the wrong moment and Shapovalov fights back to a break point.

It's dealt with - and then some - by Khachanov, who comes good after pelting successive forehands into the corner.

The Russian turns things around, seizing a first set point to take the third set!

Novak Djokovic whips down a couple of string-tenderising serves to wipe out the first two and then opts for the slice off the back of a punchy forehand to bring up deuce.