John Degenkolb and Warren Barguil were among six Giant-Alpecin cyclists hospitalised after being hit by a car while training in Spain, the German team said.
All the riders are stable after being taken to two local hospitals, Giant-Alpecin said.
The other four riders involved in the incident near the Spanish town of Calpe were German Max Walscheid, American Chad Haga, Swede Fredrik Ludvigsson and Ramon Sinkeldam of the Netherlands.
The team said that while training "a car coming the other direction rode into the group of riders head on."
Team doctor Anko Boelens told the team website that "everyone is conscious, stable and approachable."
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"Everyone is conscious, stable and approachable, but we are waiting for the latest information and consult the doctors in those hospitals about the treatments needed for the riders," said Boelens.
The 27-year-old Degenkolb of Germany has won 10 stages at the Spanish Vuelta, and several one-day races, including the Paris-Roubaix and the Milan-San Remo in 2015.
France's Barguil, 24, finished the 2015 Tour de France 14th in the general classification, and was eighth in the 2014 Vuelta.
He also won two stage at the 2013 Vuelta.
