Australia's Richie Porte has won the Tour Down Under for the second time, though for the first time in seven years he failed to win the grueling stage to the top of Willunga Hill.
Porte finished second behind unheralded Englishman Matthew Holmes on a stage he has won for the last six years after a massed breakaway on the 151.5km (95 mile) finishing stage threw the overall race standings into turmoil.
Two-time defending champion Daryl Impey entered the final stage with a two-second lead over Porte on general classification in the first World Tour event of the season.
But Impey's chances of an unprecedented third-straight win dissolved on the second of two climbs up Willunga Hill while Porte launched his trademark attack on the second climb to put the overall result beyond doubt.
Porte's chance of extending his winning streak on the Willunga stage was lost when Holmes, riding a World Tour event for the first time, swept passed him over the crown of the hill and beat him to the finish line by three seconds.
The 26 year-old from Wigan was part of a 26-rider break which sowed panic among teams whose riders were in contention for the Tour win. The breakaway maintained a lead of more than four minutes over the peloton until the first of the two climbs up Willunga Hill.
With so many riders in the break, including leading riders such as Andre Greipel, the peloton was fully stretched to close the gap. At one point the young American Joey Rosskopf, who started the day 58 seconds behind Impey on general classification and was in the leading group, held a virtual lead of more than three-and-a-half minutes on the road.
Porte's teammate, the world road champion Mads Petersen, did a superb job of leading the peloton's chase for the breakaway and it was through his efforts that Porte was able to finally launch his winning attack on the second climb.
The break began to fall apart on the first climb up Willunga Hill and completely broke up on the second as Porte drove to the front of the race. Impey couldn't go with him and dropped back to finish 30 seconds behind Porte in fifth place.
The WorldTour resumes next Sunday with the sixth edition of the Cadel Evans Great Ocean Road Race.