The short stage that exploded this Giro d'Italia into life

Stage four of 2015's Giro d'Italia, a short 150-kilometre route over the Cinque Terre along the Ligurian coast, proved as powerful as a third-week mountain stage in challenging the leading contenders and splitting the peloton today.

Italian Davide Formolo (Cannondale-Garmin) soloed to victory in La Spezia, while Australian Simon Clarke (Orica-GreenEDGE) took over the leader’s pink jersey.

Behind, the big guns fired just four days into the three-week tour. Tinkoff-Saxo tried to get Roman Kreuziger into an escape, causing Astana to take charge for Fabio Aru. Sky's Richie Porte kept pace, while Rigoberto Urán (Etixx-Quick Step) lost time.

Richie Porte said, "It felt like the Giro d'Italia finally started" — and he wasn't alone in feeling the heat after a tempestuous, dramatic stage.

Much action had been packed into the relatively short day. Porte marked Spanish favourite Alberto Contador (Tinkoff-Saxo) and Italian Aru, riding the Astana express train that not only controlled Kreuziger in that early escape, but dropped Urán. The Colombian, who finished second to Nairo Quintana (Movistar) last year, lost 42 seconds.

>>> Six talking points from stage four of the Giro d'Italia

"Aru is here to win the race," said Sky's team principal, David Brailsford. "Roman Kreuziger is a threat, and Astana brought it back.

"They rode really well — hats off to them. Aru tried on the final climb but couldn't shake everyone, and Contador and Richie followed."

The stage ran from Chiavari, inland into Liguria and then back above the famous Cinque Terre coastline. The tough terrain made up for the short ride.

Once Kreuziger, fifth in the 2013 Tour de France, made the 27-man escape and began to gain time, Astana's blue train made its first impression on the 2015 Giro.

"These are stages that you have to race well," team manager Giuseppe Martinelli said among the hundreds of fans waiting for Aru outside the bus.

"Roman was up the road, and he worried us, so we decided to shake it up. If he had not been up the road, maybe we wouldn't have done what we did, but then why not try to do something?"

Astana at one point had five riders leading the way over the small passes and through the numerous curves above the coastline. Porte and Contador were down to two helpers each, but each had men in the escape up ahead.

The stages – today 150 and yesterday 136 kilometres – are significantly shorter than the 'tappone' stages of 200 to 264 kilometres that the cyclists will face as the race continues. That perhaps made the difference and gave followers such a fascinating stage to watch.

Martinelli added: "These stages, even without big climbs, will render tomorrow's summit finish to Abetone less important."

"If you want the lads to race, then you make it short and the guys can go on the break. It forces the others to do something," Brailsford explained.

"It creates scenarios that you won't get in a 240-kilometre stage. It's a nice mixture for the first week, a short and punchy stage."

Porte congratulated his team-mates after they had finished their warm-down sessions on the turbo trainer. He appeared as happy as he was when he won any of his three big stage races this season.

The mood is much lighter around the black 'Death Star' Sky bus than it was on day one, when the team lost 20 seconds to Contador's Tinkoff team in the time trial.

The first short and punchy days down the Ligurian coast have already shaped the overall classification. Australian Simon Clarke (Orica-GreenEdge) leads the race in the pink jersey ahead of a separate 'virtual classification' of the favourites: Contador, Aru at six seconds, Porte at 20, Urán at 54, Jurgen Van den Broeck (Lotto-Soudal) at 1-04 minutes and Ryder Hesjedal (Cannondale-Garmin) at 5-49.

Astana made important gains on some rivals, but a 59.4-kilometre time trial and the high mountain stages remain on the horizon in the Giro's second half.

"There's still a long way to go," Brailsford said. "I wouldn't read too much into anything so far."