Before the start of stage 2 at the Volta a Catalunya the American had trouble walking.

On the day when French newspaper L’Equipe reported that RadioShack will end its involvement in cycling at the end of the year, there was more bad news for the team as Chris Horner was unable to start the second stage at the Volta Ciclista a Catalunya yesterday after a worrying knee injury sustained during Tirreno-Adriatico erupted during the opening stage on Monday.

The American old-timer finished sixth-overall at the Italian WorldTour event despite experiencing pain during his first race of the 2013 season and will now have the injury evaluated before returning to racing.

"Already after Tirreno he [Horner] had some knee pain," explained team director José Azevedo to Radioshackleopardtrek.com. "Yesterday in Stage 1 everything went well in the first part of the stage, but in the final the pain started all over again. This morning [Tuesday] he even had difficulty walking. Tomorrow Chris will have his knee examined in the hospital in Basel (Switzerland)," Azevedo added.