The pack of riders cycles the 186km 18th stage of La Vuelta, Tour of Spain, cycling race from Burgos to Pena Cabarga September 12, 2013. Vincenzo Nibali's overall lead in the Tour of Spain was cut to just three seconds after race rival Chris Horner dropped the Italian on the Pena Cabarga at the end of Thursday's stage 18.American Horner, who turns 42 next month, attacked close to the finish of the agonisingly steep climb to finish sixth behind stage winner Vasil Kiryienka of Belarus and gain 25 seconds on Nibali, who placed 10th REUTERS/Joseba Etxaburu (SPAIN - Tags: SPORT CYCLING)