The 148 kilometre medium mountain stage was the first test of the general classification contenders at this year’s race, which is the opening event of the International Cycling Union (UCI) WorldTour.

Czech rider Ondrej Cink and Australia’s Cameron Meyer led in the early stages of the race, which features five laps of an undulating 20km circuit.

Despite the inclines, an opportunity for bonus seconds was up for grabs in an intermediate sprint early on, with Britain’s Ben Swift triumphing to secure a three second boost.

The race was then ignited by Germany’s Jasha Sutterlin, who went solo after the sprint and enjoyed a large advantage of nearly five minutes by the 50km mark.

His lead would disintegrate towards the close of the race, as the peloton sped up in preparation of the final climb, resulting in the German being caught with 40km to go.

Orica-Scott and Movistar opted to increase the pace inside the final 10km of the race and as the route headed updwards, Porte went on the offensive.

The BMC Racing team leader would pull away from his rivals in the final five kilometres to seal the stage win in a time of 3 hours 46min and 6sec.

He would finish 16 seconds clear of Spain’s Gorka Izagirre and Colombia’s Esteban Chaves, with the Movistar and Orica-Scott riders ending in second and third respectively.

"We didn’t really race that hard around Stirling which is a bit of a shame but at the end of the day I think I got a good gap on general classification," said Porte, who will now wear the leaders' ochre jersey.

"I know it’s not over, there’s a few quite hard stages but the guys, the team, are fantastically strong so I’m quite confident."

The Australian is yet to win the six stage race but struck a potentially key blow today, with four-time winner Simon Gerrans among the pre-race favourites to be distanced today.

Gerrans, also Australian, trails the race leader by 50 seconds.

The third stage will feature a 144km route from Glenelg to Victor Harbor tomorrow.