Mauro Schmid won the 11th stage of the Giro d'Italia as Ireland's Dan Martin lost ground in the race for the pink jersey.
Following Tuesday's rest day, Martin had been eighth in the general classification ahead of Wednesday's 162km stage between Perugia and Montalcino.
But he struggled on the gravel section to slip back 10 places to 18th overall, seven minutes and six seconds adrift of leader Egan Bernal after coming home in a time of 42:42:27 in 40th.
Colombian Bernal extended his overall advantage in the general classification to 45 seconds with Russia's Aleksandr Vlasov of Team Astana-Premier Tech moving into second place, while Belgium's Remco Evenepoel dropped back to seventh overall.
Here's Dan on the gravel:— Israel Start-Up Nation / Israel Cycling Academy (@TeamIsraelSUN) May 19, 2021
Our Dan Martin lost some time on one of the gravel sections in the #Giro.
He - of course - never gives up and is doing his ultimate best to come back to the peloton.#YallaISN pic.twitter.com/oVncEmFq6L
But it was Swiss rider Schmid who crossed the line first on stage 11 in a time of 04:01:55, ahead of Italy's Alessandro Covi and Belgium's Harm Vanhoucke.
It was 21-year-old Schmid's first stage win on a Grand Tour, pulling clear of the peloton early on and battling it out with Covi after a thrilling race, before pipping the young Italian on the line to take home victory in his debut season.
Bernal remained at the head of the peloton for the majority of the stage through the Tuscan gravel roads, before making his move at the end the final climb up Passo del Lume Spento.
"Today was a really hard day," Bernal said. "We expected some big gaps and actually there were a lot of GC (general classification) riders who lost a lot of time.
"I'm happy to arrive at the front and we need to stay focused for the next days. We should be happy with this day."
Young Belgian rider Evenepoel came into the stage second and 14 seconds behind Bernal, but having kept pace early on he struggled and dropped off the peloton, with visibility poor at the back of the main group.
Nicolas Roche is 65th overall in the general classification after finishing 76th on stage 11 in a time of 43:32:28.
Thursday's Stage 12 is a 212km ride from Siena to Bagno di Romagna.