Martin (Omega-Pharma Quickstep) covered the 54km between Bergerac and Perigueux in 1:08.21, over a minute and a half faster than his nearest rival Tom Dumoulin.
There was double joy for France, who ended their 17-year wait for a podium finish in style. Nibali is almost eight minutes ahead though and should cruise to victory in Paris on Sunday.
Jean-Christophe Peraud - who finished 2:27 behind Martin despite needing a bike change during the stage - relegated his compatriot Thibaut Pinot to third place, but both men will be on the podium at the Champs-Elysees after Alejandro Valverde's challenge faded.
TT specialist Martin was delighted with his performance, and the team's.
“The victory today was another great Tour de France time trial victory added to my palmares,” Martin said. “I already won two time trials, so I am proud to now have a third win. But, I have to say, to win a road race and knowing 5km before the finish you would already win, it’s an unbelievable feeling.
“The team really did a great job for me. They paid attention to all the details. I had a clear idea of the parcours in advance. Then I went this morning to see the roads and I was really happy. It wasn’t really flat, but also not super hilly. There were always parts with two or three percent gradients, with uphills and downhills.
"You could go with a big gear, such as my 58-tooth chainring. It was just perfect for me. We discussed with Specialized before what wheels and tires we would ride, we found the right setup, and I had a good feeling the whole race on my Shiv. We used the Turbo tires that are super smooth on the road."
Peraud wept after his gut-busting ride, realising he had probably sealed a podium spot in his country's capital.
Pinot, who will win the white jersey for best young rider ahead of another Frenchman, Romain Bardet, is 8:24 back.
"Near the end I was empty, the last five kilometres felt really long," said Pinot. "I have not realised yet, I think it will sink in tomorrow."
The last time two local riders made the podium was when Laurent Fignon and Bernard Hinault finished first and second in 1984.
With just the ceremonial final stage into Paris to come, general classification positions will not change barring exceptional circumstances.
Poland's Rafal Majka will take the polka dot jersey for the mountain classification while Slovakian Peter Sagan will claim the green jersey for the points classification by a large margin. Alessandro De Marchi of Italy was voted the most aggressive rider of the race while AG2R-La Mondiale will win the team classification.
Race leader Astana team rider Vincenzo Nibali of Italy cycles during the 54-km individual time trial 20th stage …
But Nibali will be crowned overall winner, having conserved his lead of 7:52 with a solid ride, joining Frenchmen Jacques Anquetil and Bernard Hinault, Italy's Felice Gimondi, Belgian Eddy Merckx and Spain's Alberto Contador as winners of the Tour, the Giro d'Italia and the Vuelta a Espana.
The Italian, who has won four stages and worn the yellow jersey almost constantly since the early stages in Yorkshire, will be a worthy winner despite the early withdrawals of Chris Froome and Alberto Contador.
"It was not an easy time trial, it required a lot of power," said Astana rider Nibali. "I never thought about that (becoming the first Italian to win since the late Marco Pantani), I'm not sure I have realised yet."
RIDE OF THE DAY: When you go in as an odds-on favourite, it takes something special to win ride of the day – but that’s exactly what Tony Martin gave us with a ridiculously dominant performance. It would have been great to see him go toe-to-toe with Fabian Cancellara and Bradley Wiggins – but on this form it’s hard to imagine anyone in the world living with the relentless German.
And check out the mammoth 58-tooth chainring on his bike – looks more like a circular saw.
DAY TO FORGET: Few outside Spain will mourn Alejandro Valverde’s inability to muscle into the podium positions, but it was a bad day at the office for the 34-year-old, who started badly and continued to go backwards. Just 15 seconds covered Pinot, Peraud and Valverde at the start, but the latter’s failure to turn up transformed a potential nailbiter into a foregone conclusion.
THANKS FOR THE MEMORIES: 42-year-old Jens Voigt completed his final Tour de France time trial, 16 years after his first Tour. The German, legendary for his ‘Shut Up Legs’ catchphrase and uncompromising style, was able to take things a little bit easy as he soaked up the atmosphere. Watch his interview with Greg Lemond below.
HYDRATION? WHO CARES! Jean-Christophe Peraud endured a heart-in-mouth moment when he suffered a puncture and had to switch bikes. To make matters worse, he had no water bottle on the new model – but managed to make it to the end parched but triumphant.
LIKE PARISIEN BUSES: Honestly, you wait 17 years for a Tour de France podium then two come along at once.
COMING UP: The peloton travels to Evry, just south of Paris, from where they will commence a circuitous 137.5km route into the capital, culminating in the traditional sprint finish on the Champs-Elysees.
- Sports & Recreation
- Tour de France
- Jean-Christophe Peraud
- Alejandro Valverde
- Thibaut Pinot
- Bernard Hinault