(CNN) -- American Levi Leipheimer looks set to complete his second stage race victory of the season after maintaining his overall advantage after the fourth stage of the Tour of Castilla and Leon in Spain.
Leipheimer looks poised for victory in Spain after retaining his race lead going into Friday's final stage.
The mountainous 145km leg from Santa Maria del Paramo to Laguna De Las Peces was won by Spain's Juan Jose Cobo of the Fuji team, who powered up the final climb to beat Rabobank rider Denis Menchov by eight seconds.
Leipheimer finished nine seconds behind Cobo in eighth place to retain his 16-second lead over Astana team-mate Alberto Contador.
Reigning Giro d'Italia and Vuelta Espana winner Contador chose not to challenge Leipheimer for the lead -- instead working to protect the team's stranglehold on the race and keeping third-placed American David Zabriskie, who lies 22 seconds behind Leipheimer, at bay.
With the high mountains now out of the way, Leipheimer looks certain to add the title to his Tour of California victory earlier in the season, with just Friday's 152km run from Benavente to Valladolid remaining.
Seven-time Tour de France champion Lance Armstrong crashed out on Monday after fracturing his collarbone in a multi-rider pile-up.