Russia\'s Denis Menchov of the Katusha team won the 20th and penultimate stage of the Tour of Spain here on Saturday with Spain\'s Alberto Contador (Saxo-Bank) retaining the overall lead. Barring a disaster, Contador, back in the saddle after a two-year doping ban, is set for victory with just the 21st and final 115km largely flat stage from Cercedilla to Madrid to race. A 20-rider breakaway group split from the peloton after 20km, but was reduced to just three 10km out from the finish. Menchov called on all his climbing skills to notch up the stage victory 17sec ahead of Sky\'s Australian rider Richie Porte, with Belgian Kevin De Weert (Omega-Pharma) a further 25sec adrift. De Weert had dropped off the pace in the climb, but Menchov was left to see off Porte in a final desperate sprint. Contador suffered in the final gruelling ascent, but managed the essential, which was staying atop the overall standings. The Spaniard now sits 1min 16sec ahead of compatriot Alejandro Valverde (Movistar), with Joaquim Rodriguez (Katusha) in third at 1:37, the duo having taken 19 and 34sec off Contador in the day\'s stage respectively. The 21-stage race -- one of cycling\'s three \'major tours\' along with the Tour de France and the Giro d\'Italia -- ends in Madrid on Sunday after covering a total distance of 3,300 kilometres.