Welcome to live coverage of the toughest day of the 94th edition of the Giro d'Italia - a 229km trek through the mountains which features four first category climbs, including the race's highest peak.

Acqua & Sapone's Stefano Garzelli is on to the Cat.1 Passo Fedaia. Also known as the Marmolada, it features 11km of climbing at an average of 8.3 per cent. The last 6km are all more than 10 per cent while the maximum gradient is a huge 18 per cent.

Contador is with Arroyo, Anton and Scarponi as they chase down Nibali, who has quite a large gap.

Italian Garzelli has 1:25 seconds on the chasing group, which has swept up Hoogerland. Between them ride Nieve and Bakelants, at 44 seconds.

And still Garzelli's on the downhill - and he's about nine minutes ahead, which goes to show how much ground Nibali could make here on the descent.

Nibali has a sizable gap now on the descent - but we're only taking seconds. Interestingly, neither he nor Contador have any team-mates in this streamlined bunch, so come the next ascent they'll be isolated.

Meanwhile, Garzelli is still on his solo descent out at the front of the race. But back with the peloton, Nibali has already come to the front on the descent and is opening up a small gap. Dangerous, but exhilerating, riding from the Italian. And those wet roads do look slippery!

ATTACK: Contador decides enough is enough and jumps clear in pursuit of Rodriguez and Arroyo. Only Rujano can join him, but it seems more an exercise of pride than anything else. With the descent coming right up, Nibali knows he'll catch them up on the downhill.

Contador is back on the front of the peloton, alongside three team-mates. Both Nibali and Kreuziger are there too. Arroyo and Rodriguez are only just a bit further up the road - a pretty futile attempt to break, to be fair.

Garzelli moves into the lead in the mountains jersey classification with that ride - he picked up 21 points there, plus 9 earlier, meaning he's well clear of Alberto Contador for the time being. Maybe the bald Italian will be in green tomorrow?

Stefano Garzelli, wearing the No.1 bib, passes over the summit of the Giau to take the prestigious Cima Coppi prize awarded to the first rider to cross the Giro's highest peak. Nieve comes over 51 seconds down. A massively tiring Hoogerland takes third, 1:25 down, despite his early break. Nine riders then cross the line at 1:47.

ATTACK: Joaquim Rodriguez (Katusha) and David Arroyo (Movistar) break clear of the podium. They both lost a bit of time over the last two days, Arroyo in particular.

The mountain is still partially covered in snow, which explains all that liquid on the road. Garzelli has just one kilometre to ride before the summit. Five Liquigas riders lead the peloton.

Hoogerland tries to hold Garzelli's wheel but stands no chance. The Italian zooms past and will surely go on to take the Cima Coppi atop the Giau. Nieve now has Hoogerland in his sights. And they're now riding together, but it looks like the Dutchman won't be able to hold on for long.

Garzelli has Hoogerland in his sights as he passes Didi the Devil. Nieve has dropped back a touch. Back in the bunch, pink jersey Contador must have slipped back to see his team car because he's somewhat off the front.

Nieve and Garzelli are now working together in pursuit of lone leader Hoogerland, who is clearly tiring and will be caught before too long.

Garzelli has broken clear of the chasing riders in pursuit of Hoogerland and a second career Cima Coppi prize. The Italian is about one minute down, and Nieve just approaching. The others are a further 10 seconds back.

"Has anyone on this cycling thread predicted correctly a­ stage winner in this Giro?" asks Paula below. The answer is yes: this humble live commentator predicted Cav's double, plus Rujano's win. And a tip for today? Hmm... not Hoogerland, unfortunately.

Johnny gets a little tug from his team car as he picks up a fresh water bottle. Cav would be impressed by that, stylistically. Hoogerland looks exhausted. There's a lot of water on the road, possibly from a passing mountain stream. It's not rain, because the sun is still out.

Hoogerland's got more than a minute now. Meanwhile, Aramendia and Kuchyncki both drop back from the chasing group...

Since its introduction in 1965, the Cima Coppi has never been won by a Dutchman, so that might explain Hoogerland's motivation. Last year it was taken by Johann Tschopp atop the Passo di Gavia - and the Swiss rider is in with a shout today, for he's in the break. In 2009 it was Stefano Garzelli, who's also in the break. The prestigious prize has only once been fought on the Giau - back in 1973 when it was won by Spaniard Jose Manuel Fuente.

Saxo and Liquigas sharing out the duties on the front of the peloton, riding at 9:20 from the breakaway. Hoogerland has 40 seconds on the chasers as he zips down a downhill stretch before the Passo Giau starts proper.