The German made it five wins for his country at this Tour when he attacked with just under 50 kilometres remaining and held on to the finish at Pra-Loup by 32 seconds from Garmin Cannondale’s Andrew Talansky with Rigoberto Uran (Etixx-Quick Step) rounding out the podium.
“It took me two or three minutes to figure out what I had done,” said a very emotional Geschke afterwards. “It was important going into the break and then we had to figure out what to do after that.
“I had to try something. I went into a break on the long climb and I had to take my chances to win. It was beautiful. It was incredible.
“This is my third victory as a professional, to be at the Tour is… I was waiting for 15 years for this moment.”
Roche was seventh on the stage, his highest placing so far on a day where he was given a free hand by his team to chase stage victory.
He made a fine fist of it too, making his way into the day’s 28-rider breakaway along with teammate Richie Porte and they managed to pull out a maximum advantage of around four minutes on the disintegrated peloton behind.
The pressure was on Roche and Porte to deliver a result as their presence up ahead meant teammate and race leader Chris Froome only had five men for support behind following Pete Kennaugh’s withdrawal earlier in the week.
The break began to splinter as the brutality of the 161-kilometre mountain stage took its toll, but Roche was still in there with half a dozen others after Geschke made his move.
Porte, on the other hand, was summoned back to the peloton to aid Froome who was coming under ferocious attack from his closest challengers. Alberto Contador (Tinkoff Saxo) made a brave sally up the road with around 78 kilometres to go but when fellow Spaniard and GC contender Alejandro Valverde (Movistar) chased after him, it sparked a reaction from the peloton and Team Sky promptly shut it down.
Up ahead, Roche still stalked Geschke and with the help of Adam Yates (Orica GreenEdge) and Tanel Kangert (Astana) they began to chip into the deficit.
But Roche paid for his aggression on the second last climb and he was distanced by a four-man chase group containing the aforementioned Uran, Talansky, Yates and Mattias Frank (IAM Cycling).
Those five all finished ahead of Roche, as did Thibaut Pinot (FDJ) and Steven Kruijswik (LottoNL-Jumbo) but it was still a superb result from the Sky man who’s been at the service of Froome throughout this Tour.
Froome managed to defend his lead in the overall classification, following attacks from his major rivals throughout the day to finish with the same time as Nairo Quintana (Movistar).
Quintana’s teammate Alejandro Valverde lost seven seconds on Froome and Quintana but moves into third overall with the withdrawal of Tejay van Garderen (BMC).
Alberto Contador (Tinkoff-Saxo) remains in fifth but lost 2:10 on his GC rivals after crashing on the technical Col d’Allos descent. Geraint Thomas (Sky) now moves into fourth overall after finishing more than a minute ahead of Contador.
The only other Irishman, Dan Martin (Garmin Cannondale), had a difficult day, crossing the line in a large group over 21 minutes down on the stage winner.
He’ll be hoping for much better on today’s 186-kilometre stage from Gap to St Jean de Maurienne.
However, with seven categorised climbs scheduled for today including the 21-kilometre ascent of the Col du Glandon, it’s going to be another day of huge splits as the Tout nears its conclusion.