Kazakhstan's Alexandre Vinokourov upset Britain's plan to set up a massive sprint finish for Mark Cavendish when he claimed the gold medal in the Olympic road race on Saturday.
Colombian Rigoberto Uran took silver with Norway's Alexander Kristoff coming home third to win bronze eight seconds behind.
Vinokourov was part of a group that Team GB failed to rein in on the way back to central London from Box Hill. The three Irish riders all finished in the chasing peleton 40 seconds down. David McCann (55th), Nicolas Roche (89th) and Daniel Martin (90th)
Cavendish finished 29th, 40 seconds behind Vinokourov. Tour de France winner Bradley Wiggins withdrew from the race, suffering from exhaustion.
Swiss Fabian Cancellara, one of the strong men in the leading group, missed a turn and crashed into the safety barriers. He crossed the finish line 5:43 off the pace with a an apparent wrist injury.
The crash split the group up and Uran and Vinokourov pulled away to contest a two-man sprint, which the Kazakh, who was supended for two years in 2007 for blood doping, easily won.
Vinokourov announced that he would quit professional cycling after crashing out of the Tour de France last year, but could not resist the urge to get back on the bike.
Of the Irish, David McCann was eventually placed 55th, Nicolas Roche was 89th and Daniel Martin finished 90th.