Lennard Kamna landed his first Tour de France stage victory on a day when the overall race leaders saved their legs for what could be a make-or-break Wednesday.
As Germany's Kamna celebrated his maiden triumph, the picture at the top of the general classification after stage 16 remained unchanged, with Primoz Roglic and Tadej Pogacar remaining 40 seconds apart.
The peloton arrived at Villard-de-Lans a full 16 minutes and 48 seconds after Kamna crossed the line, having shown no interest at any time in following the breakaway pack.
Two monumental climbs in stage 17 could prove telling, so there was no need to exert excess energy on the 164-kilometre ride from La Tour-du-Pin.
It was nonetheless a day where a gaggle of riders out of GC contention took the opportunity to shine.
An early breakaway grew into a 23-rider squadron, splintering intermittently as the stage progressed.
Quentin Pacher made a solo break from the pack as they began the ascent to the town of Saint-Nizier-du-Moucherotte, which in 1968 hosted Olympic ski jumping, but he could not sustain the increase in pace.
The testing category one climb caught up with the Tour debutant, and his bold dart was reined in by four others, with Ecuador's Richard Carapaz (Team INEOS) leading the next burst that shook off Frenchman Julian Alaphilippe.
Kamna (Bora-Hansgrohe) and Swiss Sebastien Reichenbach (Groupama-FDJ) followed him, and it was Kamna who sprinted away to take the king of the mountain points, with Pierre Rolland having earlier claimed priceless points when he was first to climb the Cote de Revel.
This break was to prove decisive, with Kamna powering ahead on the open road to take the line first, a minute and 27 seconds ahead of Carapaz, with Reichenbach in third spot, 29 seconds further adrift.
Kamna revels in 'awesome day'
While he will not feature in the yellow jersey picture come Paris, being over an hour and a half off the overall lead, this was a momentous day in the life of Kamna. He turned 24 last week and the former team time trial world champion said of his success: "I'm feeling great - absolutely awesome day for me. It was a fight from the beginning and I knew I had to make it to the finish. When I saw Carapaz was dropping the speed, I said, 'Okay, now it's the moment to go', and then I just went on until the end."
1. Lennard Kamna (Bora-Hansgrohe) 4:12:52
2. Richard Carapaz (Team INEOS) +1:27
3. Sebastien Reichenbacj (Groupama-FDJ) +1:56
4. Pavel Sivakov (Team INEOS) +2:34
5. Simon Geschke (CCC) +2:35
1. Primoz Roglic (Jumbo-Visma) 70:06:47
2. Tadej Pogacar (Team Emirates) +0:40
3. Rigoberto Uran (Pro Cycling) +1:34
1. Sam Bennett (Deceuninck-Quick-Step) 269 points
2. Peter Sagan (Bora-Hansgrohe) 224
3. Matteo Trentin (CCC) 212
King of the Mountains
1. Benoit Cosnefroy (AG2R La Mondiale) 36
2. Pierre Rolland (B&B Hotels-Vital Concept) 36
3. Tadej Pogacar (Team Emirates) 34
The riders will be bracing themselves for an Alps stage that could prove hugely significant. Two brutal climbs await them, with the daunting Col de la Madeleine followed by a breathtaking ascent over the closing 23 kilometres, with climbs of over 20 per cent facing weary legs, culminating at the Col de la Loze. Those closing stages could provide sensational sporting drama.