Fredrik Dversnes won the fifth stage of the Tirreno-Adriatico on Friday as Filippo Ganna held his overall lead even though a mechanical failure in the finale left him trailing the peloton.
Norwegian Dversnes claimed his first ever World Tour win ahead of star riders like Tom Pidcock and Mathieu van der Poel after spending almost all of the 205km hike from Ascoli Piceno to Pergola as part of a breakaway.
"I'd had a pretty hard, cold two days, so with this (drier) weather today, it turned out to be a good stage," said Dversnes.
"Then in the final climb, I got instructions from my sports director to go all in and fortunately it turned out to be good enough. There was a pretty hard kicker up at a kilometre to go, so I wasn't sure if I could win until 500 metres to go."
Ganna is still 22 seconds ahead of Juan Ayuso in the general classification, but the Ineos rider came very close to losing his lead after his chain went with less than five kilometres remaining.
The Italian, who is a two-time time-trial world champion and a track cycling specialist, held on to the peloton throughout a long ride full of punchy climbs before nearly slipping out of contention at the last.
But he managed to just about stay with the main bunch until three kilometres to go where his time was neutralised, allowing him to stay top of the pile.
"I tried to put the chain back but it got stuck, I hit the pedal too hard and I smashed it," said Ganna to broadcaster RAI.
"I managed to get into the final three kilometres and I held my hand up to take the neutralised time, but it was close."
If Ganna is to keep the blue jersey for overall leader he will have to stay with the general classification contenders in Saturday's Queen Stage – a 163km run that ends with a summit finish of the Frontignano.
This seems unlikely given his lack of pedigree as a climber, but he said he would give it a go as the final stage is a procession to San Benedetto del Tronto on Italy's Adriatic coast.
"Yesterday and the day before weren't my type of stage either," said Ganna.
"I'm going day by day, let's see tomorrow how I'm feeling."