Australian Michael Matthews extended his Giro d'Italia lead by winning stage six to the top of the historic Montecassino climb near Naples on a day when many of the contenders for overall victory saw their chances end.

Matthews, who took the pink jersey after stage two, is a versatile sprinter and made light of the 8.5-kilometre finishing ascent which closed the longest stage of the race, the 257km route from Sassano to the Abbey at Montecassino.

His compatriot Cadel Evans (BMC Racing) was one of the main protagonists as the leaders climbed to the summit after a large crash with 11km to go split the peloton.

The sporting ethics of capitalising on others' misfortune may be debated as Evans, third overnight, moved second, 21 seconds behind Matthews by finishing third on the day, with Tim Wellens (Lotto Belisol) second.

Ireland's Nicolas Roche was among those involved in the crash and dropped to 80th. 

He lost a massive 15 minutes in general classification, a major blow to his campaign. 

Philip Deignan finds himself in 95th position, almost 18 minutes off Matthews. 

The stage was 10km longer than billed as an uncleared landslide early in the route resulted in a diversion being added.

The drama took place at the end of the stage, with Katusha's Giampaolo Caruso forced to abandon the race and taken to hospital after the day's major crash, but he was not the only victim.

Matthews' challenge for the overall title is likely to peter out as he takes a day-by-day approach to the maglia rosa, while the rivals for Evans are dwindling.

The 2011 Tour de France champion holds a 57-second advantage over third-placed Rigoberto Uran (Omega Pharma-QuickStep), who lost 49 seconds alongside fellow Colombian Nairo Quintana (Movistar), the 2013 Tour runner-up.

Uran is third, 1min 18secs adrift and Quintana sits 10th, 2mins 08secs behind Matthews, but Joaquim Rodriguez (Katusha) Michele Scarponi (Astana) and Nicolas Roche (Tinkoff-Saxo) all lost time which could spell the end of their chances.

Friday's stage is the 211km seventh stage from Frosinone to Foligno, which is likely to end in a sprint.