Porte was the clear favourite heading into the 151 kilometres route from McLaren Vale to Willunga Hill having won the stage in each of the last five years.

The stage was also viewed as key in the general classification, with South Africa’s Impey seeking to make up a seven second gap to race leader Patrick Bevin.

The New Zealand rider was cleared to start the stage after being monitored overnight following a heavy crash yesterday.

Bevin, clearly struggling with the injuries sustained, was dropped on the first ascent of Willunga as his general classification hopes came to an end.

It left Impey in the virtual race lead, with the South African forced to use his Mitchelton-Scott team in the closing stages to ensure victory.

Porte attacked from the lead group in the closing kilometres, with the home favourite catching Dutch rider Wout Poels before the finish.

He edged clear of Poels in the final metres to win the stage for the sixth time, with the Trek-Segafredo rider achieving a time of 3hr 30min 14sec.

Poels finished in second, while Impey battled through to round off the top three on the same time as the leading two riders.

The effort saw Impey clinch the general classification for the second straight year at the first International Cycling Union (UCI) WorldTour race of the season.

He enjoyed a 13 second margin of victory over Porte, who rose to second in the standings.

Poels finished a further four seconds down in third.

The Australian crowd were also able to celebrate Mat Hayman, who brought his 20-year professional career to an end.

While he was largely a domestique, Hayman's achievements include Melbourne 2006 Commonwealth Games road race gold and victory at Paris-Roubaix in 2016.