Despite being dropped twice by Rafal Majka (Tinkoff) on the second and final ascent of the Grand Colombier, Pantano appeared as if from nowhere to rejoin the Polish rider at 8.5km to go after an impressive descent.
On the run into Curloz, the pair managed to hold off the swiftly approaching Alexis Vuillermoz (AG2R) and Sebastien Reichenbach (FDJ) by six seconds, with Pantano out sprintin Majka to take Stage 15 from Bourge-en-Bresse to Culoz.
The Colombian's descent was reminiscent of his pursuit on the final descent in stage 16 of last year's Tour, only this time he took the glory rather than finishing third.
"This is incredible. It's a dream come true. I came to the Tour de France for that but I didn't believe it could happen. I've done it thanks to my team-mates," said Pantano. "I dedicate this victory to my wife. I also dedicate this win to my team captain Matthias Frank who had to pull out of the Tour because he was sick."
There was little action back in the yellow jersey group, despite the expectation that the six categorised climbs and sawtooth profile of the stage would provide fireworks. Astana tried to fire things up for Fabio Aru by driving the peloton on the first ascent of the Grand Colombier. The Kazakh team's efforts reduced the maillot jaune group to 15 riders while Nibali fell back from the breakaway on the descent to help before Aru launched his attack. He was joined by Alejandro Valverde (Movistar) but Sky reined them both in.
Romain Bardet (AG2R) then tried his luck on the Lacets but his attack lasted just moments before Sky reeled him back. Even so,Bardet's attack hurt Tejay van Garderen (BMC) who finished 1min28 behind the yellow jersey group. As a result, Richie Porte now leapsfrogs van Garderen to claim seventh on GC.
Majka now wears the polka dot jersey after claiming maximum points on the Col du Berthiand, the Grand Colombier and the Lacets du Grand Colombier. The Tinkoff rider now leads Thomas de Gendt (Lotto Soudal) in that competition by 37 points.
There was no change in the green jersey competition, with Peter Sagan (Tinkoff) retaining the green jersey. Sagan scored zero points on the stage meaning Mark Cavendish (Dimension Data) could still overhaul Sagan if his form continues to Paris.
As it happened
With the summit of the Col du Berthiand coming at kilometre 23, several riders attempted early attacks including overnight KOM leader Thomas de Gendt (Lotto Soudal). The Belgian's unsuccessful attempt to claim the 10 category one points came at a cost as he dropped to the back of the peloton as the climb went upward.
An attack by Majka and Ilnur Zakarin (Katusha) saw them clear the summit 20 seconds ahead of several pursuers. After Majka collected the maximum points for his own polka dot jersey bid the duo were joined at the bottom of the descent by 28 other riders.
This group also included the likes of Nibali, Thomas Voeckler (Direct Energie), Pierre Rolland (Cannondale), Julian Alaphilippe (Etixx-Quickstep), Alexis Vuillermoz (AG2R), and Tom Dumoulin (Giant-Alpecin). The breakaway managed to amass a lead of 5min20 by kilometre 50, which only fell to around 3 minutes by the end of the stage.
Dylan van Baarle (Cannondale-Drapac) attacked at the base of the Lacets du Grand Colombier, but Dumoulin and Nibali soon launched and passed him. Majka, Zakarin, Pantano and Vuillermoz also managed to bridge.
The remnants of the original breakaway pursued but cracked as the summit loomed. Majka and Pantano then pulled clear of Zakarin and Vuillermoz on the descent.
— CyclingCentral (@CyclingCentral) July 17, 2016