Vincenzo Nibali placed one hand on the Giro d'Italia trophy by extending his overall lead with an imperious victory on stage 18's mountain time trial.
The Astana rider stopped the clock on a testing, 20.6km course from Mori to Polsa in 44min 29sec, 58 seconds faster than second-placed Samuel Sanchez (Euskaltel-Euskadi) and 1min 20sec quicker than third-placed Damiano Caruso (Cannondale).
More significantly, he obliterated the times of his nearest rivals in the general classification, with second-placed Cadel Evans (BMC) losing to 2min 36sec to the Italian and third-placed Rigoberto Uran (Team Sky) shipping 1min 26sec.
It means Nibali, 28, who almost caught Evans, now has a 4min 2sec lead to take into Friday and Saturday's two mountain stages and it appears only a disaster, or a stunning performance from a rival, can deny him a first Giro triumph in Brescia on Sunday.
Evans's woes were compounded by the fact that his 25th-place finish was not high enough to earn him points in the race for the red jersey, which will consequently remain for another stage with Britain's Mark Cavendish (Omega Pharma - Quick-Step), who continues to lead by four points.
The course had an average gradient of 5.2 per cent and a maximum of 10 per cent, and although Nibali was among the favourites to win, the dominant manner of his victory was unexpected.
Starting last and three minutes after Evans, he was already a minute up on the Australian after 5km and had extended that to 1min 31sec at the intermediate split point, at 9.5km.
Despite the day's earlier dry conditions being replaced by rain, he continued to set a fierce pace and when he was timed at 2min 13sec faster than Evans in the closing kilometres, the prospect of a catch became a reality.
Evans managed to hang on, and will have been relieved by the fact Uran was also off the pace. The Colombian was 1min 19sec slower than Nibali at the split, but dug deep in the latter half of the course and shed only seven more seconds to the race leader. He is now just 10 seconds behind Evans in the general classification.
Earlier in the day, Britain's Steve Cummings (BMC) had posted the fastest time with a mark of 47min 8sec that would later see him finish 26th on the stage.
Compatriot Alex Dowsett (Movistar), who had won stage eight's individual time trial, suffered mechanical problems and finished 90th, 5min 27sec down on Nibali.
Cavendish was 157th, while Maxim Belkov (Katusha), who won stage nine, was eliminated from the race after stopping the clock more than 15 minutes slower than the winner.
In the young rider's classification, Rafal Majka (SaxoTinkoff) took over from Carlos Betancur (Ag2r-La Mondiale) in the white jersey after beating the Colombian by seven seconds. The duo are now separated by just two seconds.
Stage 18 result
1 Vincenzo Nibali (Ita) Astana, 44:29
2 Samuel Sanchez (Spa) Euskaltel-Euskadi, +58secs
3 Damiano Caruso (Ita) Cannondale, +1:20
4 Michele Scarponi (Ita) Lampre-Merida, +1:21
5 Rafal Majka (Pol) Saxo-Tinkoff, +1:25
6 Rigoberto Uran (Col) Team Sky, +1:26
7 Carlos Alberto Betancur (Col) Ag2r-La Mondiale, +1:32
8 Stef Clement (Ned) Blanco, +1:36
9 Dario Cataldo (Ita) Team Sky, +1:41
10 Danilo Di Luca (Ita) Vini Fantini, +1:52
1 Vincenzo Nibali (Ita) Astana, 73:55:58
2 Cadel Evans (Aus) BMC, +4:02
3 Rigoberto Uran (Col) Team Sky, +4:12
4 Michele Scarponi (Ita) Lampre-Merida, +5:14
5 Przemyslaw Niemiec (Pol) Lampre-Merida, +6:09
6 Rafal Majka (Pol) Saxo-Tinkoff, +6:45
7 Carlos Alberto Betancur (Col) Ag2r-La Mondiale, +6:47
8 Mauro Santambrogio (Ita) Vini Fantini, +7:30
9 Benat Intxausti (Spa) Movistar, +8:36
10 Samuel Sanchez (Spa) Euskaltel-Euskadi, +9:34
Red (points classification) - Mark Cavendish (Omega Pharma - Quick-Step)
Blue (mountains classification) - Stefano Pirazzi (Bardiani Valvole - CSF Inox)
White (best young rider) - Rafal Majka (Saxo-Tinkoff)