PENA CABARGA, Spain (AP) -- Vincenzo Nibali's lead over 41-year-old American Christopher Horner in the Spanish Vuelta was cut to three seconds Thursday with three days to go.
The 18th stage was won by Vasil Kiryienka of Belarus, who broke away before a final grueling ascent. He covered the 116-mile route that started in Burgos in nearly five hours.
Horner used an impressive burst to pull away from Nibali over the final 200 meters, gaining 25 seconds on his rival.
''We'll see what happens from here to Madrid,'' Nibali said. ''With what Horner has shown us, it will be difficult to withstand his attacks. But I will try to do so with everything I have.''
While Nibali maintained the lead for another day, Horner looked to be the fresher rider heading into the final days.
''Horner set an incredible pace. ... It's unbelievable what he is doing at his age'' Nibali said.
Nibali, the Giro d'Italia winner, also lost time to Joaquim Rodriguez and Alejandro Valverde. After Horner, Valverde is 1:09 off Nibali's pace and Rodriguez is 2:24 back.
This was the first of three decisive mountain stages in northern Spain before the grand tour's traditional finish in Madrid on Sunday.
With raucous crowds encouraging him up the narrow mountain road, Kiryienka had time to zip up his Sky team jersey and blow a kiss as he crossed the line.
''Five years ago I was second in a stage at the Vuelta, and I really wanted to win a stage here,'' Kiryienka said. ''I also really wanted to give something back to my team after they had believed so much in me this year.''