Scot David Millar won Saturday's 14th stage of the Tour of Spain, a 33.2 km time-trial around the town of Cuenca.
Millar completed a two-year ban in the summer
Millar finished the stage in 40 minutes 54 seconds for his first major win since returning from a two-year doping ban just before the Tour de France.
Spain's Alejandro Valverde, who finished fourth fastest on the day, retained the overall lead.
He is one minute 25 seconds ahead of Kazakhstan's Andrey Kashechkin, who came fifth in the time trial.
Millar, who was stripped of the 2003 world time trial title as part of his drugs ban, was thrilled with his victory.
"This victory proves that it is possible to race and win at the highest level in cycling without using banned drugs," he said.
"I lost everything when I got banned but now I'm back, it's fantastic.
"I was as nervous as a junior before this time trial, but I controlled my pace well and it worked out fine."
Stage 14 result:
1 D Millar (GB) Saunier 40:54
2 F Cancellara (Swi) CSC same time
3 A Vinokourov (Kaz) Astana @ 5 secs
4 A Valverde (Sp) Caisse d'Epasgne @ 13 secs
5 A Kashechkin (Kaz) Astana @ 26 secs
6 S Devolder (Bel) Discovery @ 44 secs
7 L Bodrogi (Hng) Credit Agricole @ 45 secs
8 C Sastre (Spn) CSC@ 46 secs
9 S O'Grady (Aus) Team CSC @ 54 secs
10 V Karpets (Rus) Caisse d'Epasgne @1 min 03 secs
1 A Valverde (Sp) Caisse d'Epargne 54:23.28
2 A Kashechkin (Kaz) Astana @ 48 secs
3 C Sastre (Sp) Team CSC @ 1 min 25 secs
4 A Vinokourov (Kaz) Astana @ 1 min 38 secs
5 JA Gomez Marchante (Sp) Saunier @ 2 mins 06 secs
6 J Brajkovic (Slv) Discovery @ 3 mins 49 secs
7 V Karpets (Rus) Caisse d'Epasgne @ 4 mins
8 D Di Luca (It) Liquigas @ 4 min 31 secs
9 M Beltran (Sp) Discovery @ 5 min 03 secs
10 R Marzoli (It) Lampre @ 7 mins 02 secs