Richie Porte (Team Sky) became the latest Tour Down Under rider to conquer Willunga Hill.

The Australian rider attacked in the final kilometres to take the stage win, continuing a magnificent start to his season.

The 151.5 kilometre stage began in the town of McLaren Vale and was off to a quick start with the neutral zone just 500 metres long.

Jack Bobridge (Uni-SA), who was keen to claim the KOM jersey, initiated the breakaway at the second attempt. Greg Henderson (Lotto-Soudal) and Jordan Kerby (Drapac) joined him.

The breakaway was allowed to build a quick gap by the peloton and the day's maximum time gap was 5:35 after 30 kilometres of racing. 

BMC began with the chase and held the leaders on a tight leash.

The trio up front entered the circuit at Willunga with a gap of 4:24 after 73 kilometres of racing.

After 100km of racing, Jerby was showing signs of fatigue and dropped from the breakaway.

The two leaders started the ascent up Willunga Hill chased by BMC, LottoNL-Jumbo and Astana who had brought down the gap to less than two mintues with 27 kilometres left.

Bobridge dropped Henderson soon after they hit the base of the climb and led the peloton with a gap of 40 seconds at the summit, where he grabbed the KOM points to strengthen his lead in the competition.

With 20 kilometres to go, Bobridge was caught by the 40-strong peloton.

Tensions soon arose as Lars Boom (Astana) took advantage of the crosswinds and split away from the bunch along with Dario Cataldo (Astana), Luis Leon Sanchez (Astana), Jeremy Roy (FDJ), Arnold Jeannesson (FDJ), Peter Stetina (BMC), Cadel Evans (BMC) and race leader Rohan Dennis (BMC).

However, BMC were keen to wait till the climb and did not contribute much, while back in the bunch, Orica-GreenEdge and Team Sky chased earnestly.

As the reduced peloton hit the start of the final climb in Willunga it was Simon Clarke on the front. Sky’s Geraint Thomas took over with 3.1km to the finish and led the bike race with Orica-GreenEdge’s Daryl Impey in tow until 2.2km to go.

With 1.2km to go, Porte launched an attack. Dennis, Evans and Dumoulin followed, but 100 metres later, Porte kicked again. This time, he dropped Evans and Dumoulin.

Porte set a high pace at the front and eventually managed to drop Dennis with 400m to go and finished 9 secs ahead of the race leader.

Evans and Dumoulin came in 16secs later.

With the ten second time bonus, Porte moved to second overall, two seconds behind Dennis. 

"I know this climb really, really well, better than the finish in Paracombe," Porte said after the stage. "I'm just disappointed that I came short of getting the jersey."

"The race isn’t over just yet and we will take it as it comes tomorrow, Porte added: "It is going to be hard but I haven’t lost the tour. I am second and very happy with how today went. The team was fantastic and it’s a nice way to start the season off.

"It was just stay at the front, as usual. Stay out of the wind and just follow. Luckily they set a good tempo in the front and it sort of nullified in the attacks from behind. Richie sort of went. In hindsight, probably a little bit too late because really, he had better legs than me today. I gotta thank him, but also my team is absolutely awesome," race leader Rohan Dennis said after the stage.