Richie Porte loses time as Nicola Boem surprises the sprinters

Team Sky's Porte experienced his mechanical problem inside a frantic final seven kilometres of the 200-kilometre stage up the Adriatic coast from Civitanova Marche.

Porte was given a wheel by fellow Australian Simon Clarke - who rides for rival team Orica-GreenEdge - but they were both later given two-minute penalties as their actions were in contravention of UCI ruling for "non-regulation assistance to a rider of another team”.

Australian Porte was paced over the line by four Sky team-mates 47 seconds down on the peloton.

After the two-minute penalty, Porte now trails race leader Alberto Contador by 3:09 after what was meant to be a straight-forward day in the saddle following the first rest day.

Boem - a 25-year-old Italian riding his third Giro d'Italia for Bardiani-CSF - outwitted his three fellow escapees to pick up the biggest win of his career.

On a day that looked odds-on to be a bunch sprint finale, the break rode off the front of the race for a whole 195km before holding off the onslaught behind to hold on by 18 seconds.

AGAINST ALL ODDS: Boem was part of a five-man all-Italian break alongside Alessandro Malaguti (Nippo-Vini Fantini), Matteo Busato (Southeast), Alan Marangoni (Cannondale-Garmin) and the experienced Oscar Gatto (Androni-Giocattoli).

The five leaders never saw their advantage rise much above four-and-a-half-minutes as the teams of the main sprinters kept their progress in step ahead of the expected bunch sprint.

But with local lads Marangoni and Malaguti among the escapees, the pack underestimated the task in hand.

Although the gap had dropped to 2:35 with little over 50km remaining, the peloton could not make much headway despite the work done by Andre Greipel’s Lotto-Soudal team alongside Giant-Alpecin (Luka Mezgec) and Trek Factory Racing (Giacomo Nizzolo).

When injured sprinter Matteo Pelucchi withdrew from the race with 45km to go, the Italian’s IAM Cycling team disappeared from the front of the peloton and made the task in hand even harder.

LOCAL TUSSLE: The gap was still over a minute as Malaguti led the escapees – minus Gatto, who had punctured with 13km remaining - into the outskirts of his home town of Forli.

But it was Marangoni – from the nearby town of Lugo – who made the first move; not trusting his sprint, the 30-year-old veteran of five Giros sniffed a chance at ending a career-long winless streak.

Marangoni attacked inside the final two kilometres and stayed out over a tricky cobbled section interspersed with a series of bends. Riding on his own roads, Malaguti led the chase to slash the gap ahead of the finishing straight.

But it was Boem who had the best kick, the rangy rouleur outkicking Giro debutant Busato to take the win.

A tearful Malaguti – also riding his maiden Grand Tour – crossed the line two seconds adrift, with a resigned Marangoni – who threw the die but only cast a ‘one’ – taking fourth a further two seconds back.

"I’m really happy because I so wanted to take a result on this Giro,” said Boem, riding his third home tour. "It was unexpected today on this stage but with 20 kilometres remaining we believed. Alan attacked first but I couldn’t let the opportunity go.”

PORTE PUNCTURES: Gatto’s puncture showed just how cruel the fates can be – and moments after the experienced Italian was swept up by the peloton, Sky’s Porte suffered the same harsh blow.

Despite being paced by four team-mates, Porte was unable to regain touch of the peloton, which had been led over the line by Nizzolo 18 seconds down on the stage winner.

"Bad luck happens and today it’s happened to him,” said race leader Alberto Contador, the Tinkoff-Saxo rider who dislocated his shoulder in a fall during the opening week.

"I’ve had my bad luck and now so has Richie. But tomorrow is tomorrow. There’s enough Giro left for him to challenge – and it could prove insignificant.”

Contador still leads Italy’s Fabio Aru (Astana) by three seconds in the standings, with Aru’s team-mate Mikel Landa rising to third place at 46 seconds.

Andre Greipel was the highest non-Italian rider on the stage in seventh place but it was not enough for the Lotto Soudal rider to move back into the red jersey. The German now trails Boem by 13 points, with former red jersey Elia Viviani now 20 points adrift after only mustering 16th place without a Sky lead-out at the finish.

The Giro continues on Wednesday with the 153km stage 11 which features a series of lower-category peaks before a circuit race and a fast finish in and around Imola.