Pre-race favourite Nairo Quintana quit the Vuelta a Espana after crashing for the second time in two days.
The Colombian's hopes of victory in the third and final Grand Tour of the season suffered a huge blow on Tuesday when he crashed during stage 10.
Having avoided serious injury he had hoped to race on, only to crash again, 20km into Wednesday's 153.4km stage 11.
The 25-year-old Movistar rider came down on his right shoulder and was taken away from the scene by ambulance.
The winner of the Giro d'Italia earlier this season, Quintana had been leading the Vuelta prior to Tuesday's mishap, when he misjudged a downhill section in the 36.7km individual time trial, hit the roadside barriers and went over his handlebars.
Clearly shaken by the incident, he took almost two minutes to get back on his bike, and lost another minute and a half to Spanish rival Alberto Contador in the run-in to the finish.
He would eventually come home more than four minutes down on German stage-winner Tony Martin, but crucially three minutes and 28 seconds behind Contador, who is trying to win his home Grand Tour for the third time.
This effectively ended Quintana's hopes of overall victory, but he told reporters he wanted to help Spanish team-mate Alejandro Valverde, currently in second place, overhaul Contador.
That hope is over now, with early Spanish reports suggesting Quintana may have broken his collarbone after Wednesday's crash on the run from Pamplona to San Miguel de Aralar.
Quintana's mishap is just the latest in a season dominated by high-profile crashes. Contador and British star Chris Froome were both forced to abandon the Tour de France in July after accidents, and the Giro was also hit by injury-forced retirements.
This meant, with doubts remaining over the fitness of Contador and Froome, that the Vuelta had been shaping up as perhaps the most competitive and exciting race of the season.
But with Quintana out, and Froome over a minute behind, Contador is now very much the man to beat at the halfway stage of the race.