Florence - Alberto Rui Costa stunned Spanish rival Joaquin Rodriguez at the finish line of the world championships' road race to become the first Portuguese winner of the coveted rainbow jersey on Sunday.
Rodriguez finished second to take the silver with compatriot Alejandro Valverde taking bronze at the end of rain-hit 272.2km epic that claimed several pre-race favourites as well as the entire British team.
Italy's Vincenzo Nibali had to settle for fourth after being left with no teammates for the thrilling finale in the final stages of the 10th and last lap of a hilly 16.9km circuit around Florence.
Rui Costa, who won two stages at July's Tour de France as well as the Tour of Switzerland, succeeds Philippe Gilbert of Belgium as world champion.
Gilbert's Belgian team looked among the strongest amid a reduced, 42-man field on the final lap.
However the defending champion, as well as pre-race favourite Fabian Cancellara of Switzerland, were among those unable to respond when Rodriguez countered an attack by Nibali late on the second of the circuit's three climbs.
Gilbert eventually crossed the finish line in ninth place at 34secs behind Rui Costa's winning time of 7hr 25min 44sec, with Cancellara on his wheel.
Results from the final day of the world road race championships on Sunday:
Road race (272.2 km)
1. Rui Costa (POR) 7hr 25min 44sec, 2. Joaquin Rodriguez (ESP) same time, 3.
Alejandro Valverde (ESP) at 16sec, 4. Vincenzo Nibali (ITA) s.t., 5. Andriy
Grivko (UKR) 31, 6. Peter Sagan (SVK) 34, 7. Simon Clarke (AUS) s.t., 8. Maxim
Iglinskiy (KAZ) s.t., 9. Philippe Gilbert (BEL) s.t., 10. Fabian Cancellara
11. Bauke Mollema (NED) s.t., 12. Lars Petter Nordhaug (NOR) s.t., 13.
Daniel Moreno (ESP) s.t., 14. Simon Geschke (GER) s.t., 15. Sergio Henao (COL)
s.t., 16. Michele Scarponi (ITA) s.t., 17. Filippo Pozzato (ITA) 1min 05sec,
18. Arthur Vichot (FRA) s.t., 19. Maciej Paterski (POL) s.t., 20. Edvald
Boasson Hagen (NOR) s.t.
Note: 208 riders started, 61 finished.