Hello and welcome to live coverage of what could be the key stage of this year's Giro d'Italia - it's stage 19, a mammoth 184km ride from Venaria Reale to Bardonecchia that includes the Cima Coppi - the Colle delle Finestre - a second 2,000+ metre climb to Sestriere and the final steep ascent of the Jafferau. If yesterday was tough, then this takes things to a whole new level...

They're on a wide dual carriageway in the Susa valley - and Froome is in full time-trial mode as he stretches his lead to 3'15". Amazingly, the five riders in the Dumoulin chasing group can't make any inroads, even if they're almost four minutes clear of the Pozzovivo group.

Still a long way to go - not just today but tomorrow. The final climb has some stinging double-digit sections where Froome could really hit the wall after everything he's done. And then there's the small matter of tomorrow's stage 20, which includes more climbing than we had today. Remember how Froome rode the day after his Zoncolan victory? This race is far from over, despite what people are saying.

Tom Dumoulin is in full time-trial mode now as he drags his four co-chasers along the valley. But Froome is not budging.

More than three minutes for Froome, who is writing a page of history today. He has his detractors, but you don't do what he's done today without panache, team work, a lot of luck and seriously strong legs.

There's lots of bickering going on in the second chasing group, with George Bennett having words with sandbagger de luxe Domenico Pozzovivo, while further back Pello Bilbao and Patrick Konrad gesticulate wildly after a split forms and neither wants to close it down. Everyone is fighting their own battles out there. Pozzovivo's podium dreams are disappearing while the others may drop off the top 10...

Froome isn't yet assured of the maglia azzurra: he's on 88pts (36 this morning, 45 for the Finestre, 7 for Sestriere). That puts him three-points shy of Yates. But he'll make that up over the summit.

If you're only just joining us, this is what happened on the Colle delle Finestre...

CHRIS FROOME IS THE VIRTUAL RACE LEADER! As his gap stretches up to 2'58" the Sky rider is now in the hot seat. Remember, there are still 10 bonus seconds available for the winner. But there's still that steep climb to Jafferau to go. This stage is not over yet.

CRASH: Ben O'Connor, the young Australian, crashes into the side barriers on a corner on the descent. The 22-year-old Dimension Data rider was in the Pozzovivo chasing group, which is 5'20" down on Froome and 2'25" down on the Dumoulin group. He's had a superb debut Grand Tour and is still in with a shout of making the top ten. Let's hope he can continue without too many problems.

Froome's lead is 2'45" now. Surely he'll win the stage - but will he take pink, too?

CLOSE SHAVE! A motorcyclist crashes just in front of Chris Froome in a tunnel and the Sky rider has to swing wide to avoid a collision. Thankfully, the rider is ok - it was not a serious fall - but that could have been disaster for Froome.

Froome is now in hugging-the-top-tube mode on this descent - and he's within nine virtual seconds of Tom Dumoulin's virtual pink jersey.

Over the top goes Chris Froome - and he's certain of the KOM maglia azzurra jersey tonight. But he'll want to make it pink and not blue over the next hour and a half.

Here's where they're headed - in around a kilometre's time. At least, for Froome.

Dumoulin is on the radio and perhaps he's being told that his situation is getting a little precarious... With his virtual pink lead down to 30 seconds, the Dutchman puts in a few big pulls and once again Carapaz and Lopez are struggling to match his power output.

Carapaz and Lopez - the South American white jersey rivals - appear to be lagging as Groupama duo Pinot and Reichenbach ride clear with Dumoulin.

Froome is increasing his lead on this climb... He now has 2'20" on the Dumoulin group and 3'35" on the Pozzovivo group.

Lone leader Chris Froome (Team Sky) is onto the third and penultimate climb, the Cat.3 ascent to Sestriere. In its entirety it's 16.2km long but the first bit has only been a gradual false flat. He's now onto the steeper 6% section. It will hit a maximum 9% around 6km from the summit.

The gap is up to 1'55" for Froome. It's an intriguing situation: Froome is on his own and could easily blow if he pushes it so hard, so early. Dumoulin, however, has other riders with him here, and if he remains calm then, in theory, it should be ok. But he really needs others to help out here, and only Pinot and Reichenback are prepared to do so. The lightweight climbers Lopez and Carapaz are doing ziltch - as is to be expected. The Dutchman leads them through the intermediate sprint to take two bonus seconds.

Sebastian Reichenbach has managed to fight back into the chasing group where he's helping his Groupama-FDJ leader Thibaut Pinot. The Frenchman could be up into third place tonight with his podium ambitions revived. Meanwhile, Froome wins the intermediate sprint at Pragelato to pick up three extra bonus seconds...

Froome is taking some serious risks here on the descents, cutting corners and throwing scant caution to the wind. But that's the nature of his - and his team's - ride today: they've gone for broke and what we're being treated to could be the most spectacular day's racing in modern history. He's 1'30" ahead of the Dumoulin group, 2'35" ahead of the Pozzovivo group and 15'10" ahead of Simon Yates.