Giro d'Italia: Vincenzo Nibali storms to victory in stage 18

Italy's Vincenzo Nibali convincingly won stage 18 of the Giro d'Italia to extend his lead over Cadel Evans in the overall standings.

Nibali was in supreme form in the mountainous 20.6km time trial to Polsa, winning in 44 minutes 29 seconds.

He beat second-placed Sammy Sanchez by 58 seconds and stretched his lead over Evans to more than four minutes.

Evans finished the stage in 25th position, meaning Mark Cavendish retains the red points leader's jersey.

Cavendish led the standings on 113 points at the start of the stage, four clear of Evans, but with the terrain being too hilly for the British rider to add to his points tally, Evans knew a top-12 finish would see him take the red jersey.

It was no surprise that Cavendish's time of 52'34" was more than eight minutes down on Nibali, but it was a shock to see Evans, who is usually a decent time triallist and climber, finish two minutes 36 seconds adrift of Nibali.

Britain's Cavendish is aiming to join an elite group of four riders to win the points jersey at each of the three Grand Tours, having already won the Tour de France and Vuelta a Espana equivalents.

However, he can realistically only win the sprinter-friendly last of the three stages remaining in the race, and by then Evans or Nibali, who is only 10 points back after Thursday's victory, could be unsurpassable.

Stage winners pick up 25 points towards the red jersey classification and with the next two stages in the Dolomite mountains, Nibali and Evans are likely to pick up more points.

Race leader Nibali was the last to start the time trial and set off three minutes after second-placed Evans but almost caught his rival by the finish.

Astana rider Nibali was 92 seconds quicker than Evans through the first checkpoint and continued to catch the BMC Racing team's number one racer on the second half of the climb, which featured gradients of 10%.

Nibali punched the air with his right arm as he crossed the line in scenes reminiscent of Sir Bradley Wiggins when he won the final time trial on his his way to becoming the first British winner of the Tour de France last year.

The 28-year-old Italian, who is seeking his second Grand Tour win after claiming the 2010 Vuelta, is four minutes two seconds ahead of Evans.

"I have a significant advantage now and that will allow me to control the coming two stages in more tranquil fashion," said the Italian.

Evans retained second place but Team Sky's Rigoberto Uran, who consolidated his third place by finishing 1'26" behind Nibali, moved to within 10 seconds of the Australian.

British time trial champion Alex Dowsett, who won the stage eight time trial, suffered a mechanical problem and was forced to change bikes as he finished well down the field.

Fellow Briton Steve Cummings, who set the early lead, finished 26th, 2'39" off the pace.

Friday's mountainous stage is scheduled to take in the Gavia and Stelvio mountain passes but snow is forecast and temperatures atop the mountains have been reported to be -14C.

Race directors are monitoring the weather conditions in the Dolomite mountains and will decide in the morning whether the race has to be re-routed through the valleys.

Stage 18 result:

1. Vincenzo Nibali (Ita/Astana) 44:29"

2. Samuel Sanchez (Spa/Euskaltel) +58"

3. Damiano Caruso (Ita/Cannondale) +1'20"

4. Michele Scarponi (Ita/Lampre) +1'21"

5. Rafal Majka (Pol/Saxo - Tinkoff) +1'25"

6. Rigoberto Uran (Col/Team Sky) +1'26"

7. Carlos Betancur (Col/AG2R) +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"

General classification standings:

1. Vincenzo Nibali (Ita/Astana) 73:55:58"

2. Cadel Evans (Aus/BMC Racing) +4'02"

3. Rigoberto Uran (Col/Team Sky) +4'12"

4. Michele Scarponi (Ita/Lampre) +5'14"

5. Przemyslaw Niemiec (Pol/Lampre) +6'09"