Richie Porte (Team Sky) soloed to victory after a devastating show of strength on Willunga Hill, but narrowly missed out on grabbing the ochre jersey on stage five of the Tour Down Under.

The Australian repeated his victory of 12 months ago, after two unanswerable attacks on the final ascent, but ochre jersey Rohan Dennis (BMC Racing) claimed second place, nine seconds in arrears, to maintain a slender two-second lead.

With only a pan-flat circuit of Adelaide to come, it means Porte will be relying on picking up some unlikely bonus points if he wants to top the podium in his home race.

Nevertheless, for the second season running he showed he is entering the season in top form as he left his rivals for dead on the 3.5km ascent.

Fellow Aussie Jack Bobridge also had cause to celebrate after another day in the break ensured he will win the King of the Mountains classification.

The stage one winner, riding the race in preparation for his assault on the UCI Hour Record, was active from the start once again and eventually went clear with Greg Henderson (Lotto-Soudal) and John Kerby (Drapac).

Though Bobridge was still handily placed overall, with little expected of him on Willunga Hill the peloton was content to let them go – with BMC Racing setting the pace in the bunch.

Henderson was allowed to bag the intermediate sprint points as the lead peaked at more than five minutes but was quickly reeled in – not least after Kerby sat up and returned to the bunch.

The advantage was down to less than two minutes as they hit Willunga Hill for the first time, with the big GC teams working hard to place their riders in a good position in the bunch.

Dennis, Cadel Evans (BMC Racing), Porte, Michael Rogers (Tinkoff-Saxo) and Luis Leon Sanchez (Astana) were all among the riders to move forwards as Bobridge – aided by a hand-sling from Henderson – pressed on to claim the King of the Mountains points.

He was reeled in on the descent, with Astana hitting the front and BMC Racing, Team Sky and Tinkoff-Saxo happy to sit in behind them.

A big turn from Astana’s Lars Boom saw Porte and his Sky team-mates caught behind a split but the considerable firepower of Geraint Thomas and Peter Kennaugh brought everything back together in the ever-decreasing peloton.

Orica-GreenEDGE initially took charge as they hit Willunga Hill for the second and final time, with all of the favourites in the front group of 25 riders on the lower slopes.

When Porte attacked, he attacked hard however and had soon shredded that group – Tom Dumoulin (Giant-Alpecin) and Rohan Dennis (BMC Racing) the only riders to find his wheel.

Another burst of pace accounted for those two, as he soloed to victory for the second year running, with all eyes then turning to the clock.

But with two seconds to spare, Dennis crossed in second place to set up what could be the biggest win of his career to date.

Tour Down Under 2015: stage five – result

1) Richie Porte (AUS) – Team Sky – 3.37.32hrs
2) Rohan Dennis (AUS) – BMC Racing +9”
3) Ruben Fernandez (ESP) – Movistar +16”
4) Cadel Evans (AUS) – BMC Racing – ST
5) Tom Dumoulin (NED) – Giant-Alpecin
6) Domenico Pozzovivo (ITA) – Ag2r-La Mondiale +19”
7) Tiago Machado (POR) – Katusha +24”
8) Moreno Moser (ITA) – Cannondale-Garmin +26”
9) Gorka Izaguirre (ESP) – Movistar +28”
10) Arnold Jeannesson (FRA) – FDJ.fr – ST

General classification

1) Rohan Dennis (AUS) – BMC Racing – 17.19.09hrs
2) Richie Porte (AUS) – Team Sky +2”
3) Cadel Evans (AUS) – BMC Racing +20”
4) Tom Dumoulin (NED) – Giant-Alpecin +22”
5) Ruben Fernandez (ESP) – Movistar +24”
6) Domenico Pozzovivo (ITA) – Ag2r-La Mondiale +31”
7) Daryl Impey (RSA) – Orica-GreenEDGE +38”
8) Tiago Machado (POR) – Katusha +46”
9) Gorka Izaguirre (ESP) – Movistar +52”
10) Jarlinson Pantano (COL) – IAM Cycling +53”