In a separate crash, Tony Gallopin suffered a broken wrist, with his AG2R La Mondiale teammate Oliver Naesen bruising his pelvis but escaping without a fracture.
Foss was hoping to make an impact as one of a wave of young talents in the pro peloton, and was even looking to perform on the steep uphill finish at Cullera.
However, just 5km from the line, he lay stricken in the road. It's unclear how exactly the crash happened but Foss landed on his right shoulder. He was soon back on his feet but it was clear he could play no further part in the race.
After being taken to hospital, X-Rays confirmed he had broken his right collarbone.
"What a start to my pro career, haha," Foss wrote on Twitter. "A broken collarbone that needs a surgery is the case, so I am happy it didn’t went worse [sic]! Huge thanks to the team for taking good care of me and thanks for all the messages! I will be back soon."
Foss' injury is another setback for the Jumbo-Visma team, who lost Tom Dumoulin to illness on the eve of the race. In the former Giro d'Italia winner's absence, it was hoped Foss could step up and lead the line for a general classification bid, but the Dutch team have already won a stage through sprinter Dylan Groenewegen, who has another couple of opportunities in front of him.
"We had hoped that he [Foss] could have joined the battle on this kind of finish," said director Grischa Niermann. "This is very annoying for him and for the team. But this is part of cycling as well."
There was also frustration over at the AG2R camp, with Gallopin sustaining another injury in what has been a crash-ridden couple of years. The Frenchman hit the deck with 15km to go and fractured the scaphoid bone in his left wrist.
He finished the stage but will not start Friday's stage 3, and his recovery time will be determined in due course, according to the team.
Speaking to Cyclingnews in November, Gallopin voiced his frustration at the way bad luck have derailed his ambitions in the past two seasons.
"Beforehand I almost never crashed, but in the past two years it’s been every other race," he said. "It’s been a spiral."
Gallopin's teammate Oliver Naesen was also involved in the crash and took a blow to the pelvis. He limped to the finish, 12 minutes behind the leaders, but fracture was ruled out and he was cleared to continue in the five-day race.
What a start to my pro career, haha🙃 A broken collarbone that needs a surgery is the case, so I am happy it didn’t went worse! Huge thanks to the team for taking good care of me and thanks for all the messages!🙌🏽 I will be back soon😊🤟🏽 @JumboVismaRoadFebruary 6, 2020