Wilco Kelderman seized the maglia rosa from Joao Almeida after a memorable 18th stage of the Giro d'Italia was won by Jai Hindley to blow the race wide open.
The 207-kilometre route from Pinzolo to Laghi di Cancano provided drama aplenty, ending with a new race leader and a stage win for Hindley, who sits second in the General Classification, 12 seconds back from fellow Team Sunweb rider Kelderman.
The daunting Passo dello Stelvio was where the cracks showed for Almeida, the 25km climb to an altitude of 2,758 metres all but ending his hopes of glory as his 17-second advantage gave way to a deficit of over two minutes.
Almeida had described the slog up to the Giro's highest point as "great" before Thursday's stage, but he may take a different view after he was dropped with just under 50km to go, losing the virtual lead to Kelderman.
But the Dutchman was facing a battle to keep up with a leading group featuring Tao Geoghegan Hart, himself now firmly in the shake-up at 15 seconds off the GC leader.
The INEOS Grenadiers rider was joined at the front by Hindley and team-mate Rohan Dennis, who was in eye-catching form as he ascended the Cima Coppi.
It was a blistering pace that put paid to any chance Vincenzo Nibali had of triumphing as the veteran fell out of contention, even before the 21 hairpins heading towards the finish line at Laghi di Cancano.
With Dennis' race run, Geoghegan Hart and Hindley contested the sprint on an uphill finish and it was the Australian who crossed the line first to earn a time bonus that put him ahead of his British rival in riveting race now led by Kelderman.
STAGE RESULT
1. Jai Hindley (Team Sunweb) 06:03:03
2. Tao Geoghegan Hart (INEOS Grenadiers) +00:00
3. Pello Bilbao (Bahrain-McLaren) +00:46
4. Jakob Fuglsang (Astana Pro Team) +01:25
5. Wilco Kelderman (Team Sunweb) +02:18
CLASSIFICATION STANDINGS
General Classification
1. Wilco Kelderman (Team Sunweb) 77:46:56
2. Jai Hindley (Team Sunweb) +00:12
3. Tao Geoghegan Hart (INEOS Grenadiers) +00:15
Points Classification
1. Arnaud Demare (Groupama-FDJ) 221
2. Peter Sagan (Bora-Hansgrohe) 184
3. Joao Almeida (Deceuninck-Quick-Step) 94
King of the Mountains
1. Ruben Guerreiro (EF Pro Cycling) 234
2. Thomas De Gendt (Lotto-Soudal) 122
3. Tao Geoghegan Hart (INEOS Grenadiers) 115
WHAT'S NEXT?
Stage 19 largely spares the riders any further punishment on the climbing front, but they must still cover 258km from Morbegno to Asti. With a flat final 5km, this is one for the sprinters.