Race organisers were forced to remove the first of the day’s two major climbs due to snow, ice and freezing temperatures.
But the final summit finish to Jafferau remained and Nibali attacked on the steep climb to extend his lead over Cadel Evans (BMC Racing) by 33 seconds.
The race returned to the high mountains for the first of two back-to-back summit finishes. The 2013 edition of the Giro has been dogged by bad weather and that continued in the Alps, prompting the diversion of the stage to avoid the long climb to the ski resort of Sestriere.
That made the stage 12km longer but largely kept the race on the valley floor until the final ascent. The poor weather also disrupted television coverage of the stage with the transmission helicopters unable to take off due to low level cloud.
Four riders – Luca Paolini (Katusha), Sonny Colbrelli (Bardiani), Daniele Pietropolli (Lampre-Merida) and Matteo Trentin (Omega Pharma-QuickStep) – escaped with approximately 100km of the new 180km route remaining and reached the bottom of the final climb with a lead of four minutes.
Team Sky drove the peloton to the foot of the climb, which has an average gradient of nine per cent over 7.3km, in a bid to setup Rigoberto Uran, the squad’s team leader following the withdrawal of Bradley Wiggins.
But, with the breakaway swept up on the climb, it was Nibali who once again dictated proceedings, attacking with one kilometre to the summit. Only the Italian’s compatriot, Santambrogio, was able to go with him and Nibali, who secured a 12-second time bonus for finishing second, was happy to gift the 28-year-old the stage.
Carlos Betancur (Ag2r La Mondiale) crossed the line nine seconds later in third, while Samuel Sanchez (Euskaltel-Euskadi), Uran and Evans then followed in quick succession.
Nibali now leads Evans by one minute and 26 seconds, while Uran remains third, two minutes and 46 seconds adrift of the maglia rosa, and only one second ahead of Santambrogio.
Stage 15 was due to cover an epic 149km route via Mont Cenis before crossing into France for a summit finish atop the Col du Galibier at 2,642m but that course has also been altered and will instead finish 4.25km from the Galibier summit at the Marco Pantani memorial due to heavy snow at the top of the mountain pass.
Giro d’Italia 2013 – stage 14 – result
1) Mauro Santambrogio (ITA) – Vini Fantini-Selle Italia – 4:42:55 hours
2) Vincenzo Nibali (ITA) – Astana – same time
3) Carlos Betancur (COL) – Ag2r La Mondiale +9 ”
4) Samuel Sanchez (SPA) Euskaltel-Euskadi +26″
5) Rigoberto Uran (COL) – Team Sky +30″
6) Cadel Evans (AUS) – BMC Racing +33″
7) Domenico Pozzovivo (ITA) – Ag2r La Mondiale – same time
8) Robert Kiserlovski (CRO) – Radioshack Leopard – same time
9) Sonny Colbrelli (ITA) – Bardiani Valvole-CSF Inox +55″ 10 Damiano Caruso (Ita) Cannondale Pro Cycling 0:00:58
1) Vincenzo Nibali (ITA) – Astana – 57:20:52 hours
2) Cadel Evans (AUS) – BMC Racing +1’26”
3) Rigoberto Uran (COL) – Team Sky +2’46”
4) Mauro Santambrogio (ITA) – Vini Fantini-Selle Italia 2’47”
5) Michele Scarponi (ITA) – Lampre-Merida +3’53”
6) Przemyslaw Niemiec (POL) – Lampre-Merida +4’55”
7) Domenico Pozzovivo (ITA) – Ag2r La Mondiale +5’12”
8) Rafal Majka (POL) – Saxo-Tinkoff 5’32”
9) Carlos Betancur (COL) – Ag2r La Mondiale +5’39”
10) Benat Intxausti (SPA) – Movistar +5’51”