Blood had been expected along the zigzagging paths towards La Planche des Belles Filles but not such an abrupt kill. Yet on another wild day at this year’s Tour de France two moments of the highest drama tilted this year’s race perhaps decisively towards the Italian Vincenzo Nibali.

The first came halfway through stage 10, high up Le Markstein, where the air was thinned of oxygen and thickened with fog. Even so, one could make out Alberto Contador – his right tibia broken after an early crash – patting his Saxo-Tinkoff team-mate Michael Rogers fondly on the back, before struggling off his bike and into his team car.

Two hours later Nibali – teeth clenched, yellow helmet jigging excitedly – surged past his rivals in a curt display of acceleration and authority to win the stage, 15 seconds clear of Thibault Pinot with Alejandro Valverde five seconds further back in third.

It was on La Planche des Belles Filles two years ago that Team Sky blasted the peloton apart, with Chris Froome winning the stage and Bradley Wiggins slipping into yellow. This time Nibali did it solo, powering past Joaquim Rodríguez with 1.2km to go, to regain the yellow jersey he had relinquished on Sunday.

If the Italian keeps his form it is hard to see him losing the Tour now. Certainly Sky’s Richie Porte, who finished 25 seconds behind on the day to move into second on general classification, 2min 23sec behind, knows it will be hard to find a weakness that is yet to reveal itself. Porte said: “I felt good but it’s not great to be towing everyone to the line. But when Vincenzo goes you have to respond. He’s got enough time already. You don’t really want him to get any more.”

Facebook Twitter Pinterest Vincenzo Nibali heads to the finish line. Photograph: Bryn Lennon/Getty Images

Inevitably thoughts returned to Contador – the latest high-profile victim of a race that has now lost Mark Cavendish, Froome and him in the opening 10 days. The Spaniard, favourite for this year’s Tour after Froome abandoned with a broken wrist, had attempted to ride on after crashing on the descent of the day’s second climb, the 1,163m Petit Ballon. But as the yellow jersey group drifted away, pain and reality bit hard.

There were rumours that Contador’s bike frame had snapped, causing him to fall. It was also suggested that a bike had fallen off the team car and on to Contador. Both were denied by Saxo-Tinkoff. Once TV cameras had missed the crash, speculation was inevitably going to follow.

Later the Belgian rider Jurgen van den Broeck said that Contador had crashed trying to overtake the peloton on the descent of the Petit Ballon, when he hit a pothole in the road at 65kph and flew over his handlebars. Other riders said Contador hit a rock.

It took time for the medical team to reach him and for his right knee to be wrapped; time too for his bike to be fixed and cleats altered. When Contador finally got moving he had lost four minutes on the peloton. Progress was interrupted twice more: to talk to his Saxo-Tinkoff sporting directeur, Bijarne Riis, and then to speak to the medical wagon.

It was all to no avail. Contador kept going for another 20km but with 77km of the stage remaining he decided to abandon.

Spain's Alberto Contador covers his face. Photograph: Christophe Ena/AP

The tone for the day was set from the moment the Tour director, Christian Prudhomme, lowered his flag and a group of desperados charged away from the peloton on the flat 20km out of Mulhouse. Many of those in the breakaway were French, keen to show their faces and sponsor’s jerseys.

Among them was Tommy Voeckler, who even at 35 craves attention more than a precocious toddler. Also there was Tony Martin, in spite of Sunday’s heroics where he had ridden 59km solo to win the stage into Mulhouse, trying to get his Omega Pharma-Quickstep team-mate Michal Kwiatkowski into yellow. But the man making the most striking impression was Purito Rodríguez. The Spaniard has expected very little from himself on this Tour, after injuring himself in a crash in the Giro in May, yet rode himself into the King of the Mountains jersey.

With 20km remaining energy suddenly drained from Martin’s legs and it was enough for the German to haul his bike up the road. While Kwiatkowski and Rodríguez pressed on, the Lotto-Belisol group of Tony Gallopin chugged away in metronome, trying to keep possession of the maillot jaune. On Sunday night Gallopin received a congratulatory call from the French president François Hollande, while having a massage. Now there was suffering of a different kind.

It all came down to the day’s final climb. La Planche des Belle Filles has a lyrical name derived from a grizzly legend: an apocryphal story in which local girls, fearing torture by the Swedish Army in the thirty years’ war, killed themselves by jumping into a lake. Afterwards a soldier engraved an epitaph for the beautiful girls on a board. This time it was Rodríguez writing his own epitaph, first leaving Kwiatkowski behind and then leaving Rodríguez – and spectators – gasping.

Today the riders have their first rest day, although Nibali appears to have plenty in the tank. A few minutes before his devastating final strike he was happily chatting to his his team-mate Jakob Fuglsang. The evidence suggests that it is his to lose. Then again, given what has happened in the Tour so far, it would be foolish to be too forthright in predictions.