"It was a really hard blow. The barrier of the housing estate went down before I was through, and I hit straight on with my arms and chest," Valverde said. "I tried to continue the training ride but I could only carry on for half an hour because of the pain."
Valverde's presence at Thursday's Vuelta a España route presentation is now uncertain, depending on how well he can recover.
"I hope that with ice and anti-inflammatories it doesn't go any further, but I suppose that tomorrow in the cold it could get worse," he said. "The good thing is that it appears to be all muscular, but the truth is that right now I almost can't move."
Assuming he is well enough healed by the final week of January, the 36-year-old Spaniard is set to get his racing season underway at the Mallorca Challenge.