Britain's Chris Froome of Team Sky tightened his grip on the Tour de France yellow jersey after winning the 17th stage time trial on Wednesday.
Froome, taking his third stage win of the 100th edition, finished the hilly 32 km race against the clock in a time of 51min 33sec to beat Spanish rival Alberto Contador by nine seconds.
Saxo team leader Contador's time of 51:42 looked good enough to give the Spaniard his first stage win of this year's race but in the end it served only to move him up to second overall at 4:34 behind Froome.
But after Froome swapped his bike for a time trial machine just befor the summit of the Cote de Reallon, the Briton powered over the remaining 12 kilometres to overhaul the 11-sec deficit he had to Contador at the summit.
Asked if he thought that made the difference, Froome said: "That was our strategy, but it was more about the gearing. It allowed me to go faster on the second half of the course and I think it was the right choice."
After stepping off the podium, where he made three visits for the stage win, the yellow jersey and the best climber's polka dot jersey, Froome said his win was unexpected.
"Visiting the podium three times was just incredible," said Froome, who was supported along the route by many fans waiving British flags.
"I'm really happy with the result from today. I wanted to hold back a little bit for the days ahead and I was actually prepared to lose a little bit of time, so I'm quite surprised I won the stage."
Coupled with the threat of rain for the late starters, many riders faced the dilemma of deciding whether to swap their habitual road race bikes for time trial machines at the summit of the day's final climb, which was followed by a far less technical descent than the descent of the Puy-Sanieres climb at the 25.5 km mark.
Contador was one of the few favourites who opted to use his normal bike, albeit with aero bars fitted to the handlebars.
His team mate Roman Kreuziger finished the stage 23sec adrift of Froome, moving the Czech up to third at 4:51 overall as Dutchman Mollema flattered to deceive in a discipline known as the 'race of truth'.
Mollema was in second overall overnight at 4:14, having revived hopes in his native Holland of a rare podium finish in Paris.
However the Belkin team leader struggled to match the leading contenders.
After narrowly escaping a crash on the final bend, barging into the barriers after badly negotiating a right-hand bend, Mollema came over the finish 2:09 behind Froome.
Spaniard Joaquim Rodriguez of Katusha finished third on the stage at 10secs behind Froome and one behind Contador while another strong climber, Alejandro Valverde (Movistar) was fifth at 30secs off the winning pace.
The 18th stage on Thursday is a 172.5 km race beginning in Gap and featuring six climbs, including two ascensions of the legendary Alpe d'Huez, which will also host the finish.
Full report to follow
Overall standings after the 17th stage of the Tour de France, a 32.0km time trial from Embrun to Chorges on Wednesday:
1. Chris Froome (GBR/SKY) 66hr 07min 09sec
2. Alberto Contador (ESP/SAX) at 4:34.
3. Roman Kreuziger (CZE/SAX) 4:51.
4. Bauke Mollema (NED/BKN) 6:23.
5. Nairo Quintana (COL/MOV) 6:58.
6. Joaquin Rodriguez (ESP/KAT) 7:21.
7. Laurens ten Dam (NED/BKN) 8:23.
8. Jakob Diemer Fuglsang (DEN/AST) 8:56.
9. Michal Kwiatkowski (POL/OPQ) 11:10.
10. Daniel Martin (IRL/GRM) 12:50.
11. Michael Rogers (AUS/SAX) 13:19.
12. Alejandro Valverde (ESP/MOV) 15:12.
13. Andrew Talansky (USA/GRM) 15:13.
14. Daniel Navarro (ESP/COF) 16:43.
15. Maxime Monfort (BEL/RSH) 17:04.
16. Andy Schleck (LUX/RSH) 23:34.
17. Mikel Nieve (ESP/EUS) 23:36.
18. Cadel Evans (AUS/BMC) 24:44.
19. Daniel Moreno (ESP/KAT) 27:35.
20. Romain Bardet (FRA/ALM) 28:43.