Riders on Sunday had to make two climbs to the summit of Willunga Hill. The first half of the climb is the steepest, before a slightly less grueling last two kilometers to the peak. That has been where Porte has made his attacks in recent years.
He tried to do so again but his plan was complicated by Team Sky Riders Kenny Elissonde and Wout Poels who pressed the issue at the front of a leading group of 60 riders which included Porte and Impey. When Porte finally went, late on the second climb, it may have been too late.
Impey, with close support from his Mitchelton Scott teammates, kept in touch with Porte and was credited with the same time as the Australian when he crossed the line.
On general classification he finished 13 seconds ahead of Porte while Poels took third place a further six seconds behind.
“I’m pretty stoked of course with the bike ride,” Impey said. “I accepted the pressure but of course I had faith in my team which goes a long way.”
The WorldTour continues later this month with the one-day Cadel Evans Great Ocean Road Race in Geelong, Victoria, Australia, on Jan 27.