UPDATE – Richie Porte has received a two-minute penalty for non-regulation assistance, with Simon Clarke (Orica-GreenEDGE) receiving the same punishment.

Nicola Boem (Bardiani-CSF) won stage ten of the Giro d’Italia as the sprint teams failed to reel the day’s break back in as racing resumed after the rest day.

Boem was the beneficiary on a day of surprising drama, which also saw Richie Porte (Team Sky) lose time to Alberto Contador (Tinkoff-Saxo) and Fabio Aru (Astana) after a late mechanical.

After an intense nine days up until the first rest day, a flat stage was expected to offer a gentle welcome back to racing but instead produced another enthralling day.

Five riders attacked early in the stage, include breakaway regulars Boem, Alessandro Malaguti (Nippo-Vini Fantini) and Alan Marangoni (Cannondale-Garmin).

Oscar Gatto (Androni Giocattoli-Sidermec) and Matteo Busato (Southeast) completed the all-Italian move and they were left out all day by a relaxed peloton.

Race leader Alberto Contador (Tinkoff-Saxo) was among those seen chatting and joking in front of the TV motos, while Lotto-Soudal contributed to the chase on the front.

Matteo Pelucchi (IAM Cycling), even with such a relaxed mood in the peloton, had to call time on his race, however, forced to concede defeat after not recovering from the injuries he suffered in the stage two crash.

The gap to the front group never appeared too threatening but with 20km remaining it still stood at more than two minutes as the front men pushed on well.

Gatto suffered a disastrously-timed mechanical in the front group, however, which ensured he had to give up on his hopes of staying out until the finish.

Even without Gatto though, the gap refused to come down – even with Lotto-Soudal starting to up the pace in a panicked response.

Gatto was not the only rider to suffer an untimely mechanical, either, as Porte was halted with little more than five kilometres remaining.

Several team-mates dropped back to support the Australian – who had already been helped out by Orica-GreenEDGE’s Simon Clarke after suffering a puncture.

This is cycling. This is the best sport in the world. #Giro pic.twitter.com/gK4C4YfSg9

— Giro d’Italia (@giroditalia) May 19, 2015

Marangoni was the first to attack from the front group, on the cobbled finale, passing under the flamme rouge with a small advantage.

Marangoni took the sprint up front but Boem caught his wheel and passed him on the final straight to claim victory.

Giacomo Nizzolo (Trek Factory Racing) led the peloton in, with Contador and Aru safe in the bunch, as eyes then turned to the clock.

Porte, with team-mates for company, pressed on hard to limit their losses but the Team Sky man’s second week started in the worst possible fashion – dropping out of the top three overall.

Giro d’Italia 2015: stage ten – result

1) Nicola Boem (ITA) – Bardiani-CSF – 4.26.16hrs
2) Matteo Busato (ITA) – Southeast – ST
3) Alessandro Malaguti (ITA) – Nippo-Vini Fantini +2”
4) Alan Marangoni (ITA) – Cannondale-Garmin +4”
5) Giacomo Nizzolo (ITA) – Trek Factory Racing +18”
6) Sacha Modolo (ITA) – Lampre-Merida – ST
7) Andre Greipel (GER) – Lotto-Soudal
8) Luka Mezgec (SVN) – Giant-Alpecin
9) Nicola Ruffoni (ITA) – Bardiani-CSF
10) Davide Appollonio (ITA) – Androni Giacottoli-Sidermec

General classification

1) Alberto Contador (ESP) – Tinkoff-Saxo 42.58.09hrs
2) Fabio Aru (ITA) – Astana +3”
3) Mikel Landa (ESP) – Asana +46”
4) Dario Cataldo (ITA) – Astana +1.16
5) Roman Kreuziger (CZE) – Tinkoff-Saxo +1.46
6) Rigberto Uran (COL) –Etixx-QuickStep +2.10
7) Giovanni Visconti (ITA) – Movistar +2.12
8) Damiano Caruso (ITA) – BMC Racing +2.20
9) Andrey Amador (CRC) – Movistar +2.24
10) Leopold Konig (CZE) – Team Sky +3.09