Defending series champion Shane van Gisbergen has set a new lap record to dominate Supercars practice at Perth.

The flying Kiwi clocked 54.78 seconds on the tight 2.4km circuit – shaving 0.21 of a second off Holden teammate Jamie Whincup’s 2011 practice mark.

Ford’s Fabian Coulthard – the series leader – was also under Whincup’s old mark in 54.79 to finish second fastest in Friday’s final 45 minute practice session.

Six-time series champion Whincup was third quickest.

Mark Winterbottom was fourth fastest, while Ford teammate Chaz Mostert completed the top five.

The sole red flag emerged midway through the final practice session after 16-year-old Alex Rullo made contact with Whincup, locked it up and found the sand on turn seven.

Holden’s Garth Tander was fastest in the opening practice session in 55.64 seconds.

Qualifying for Perth’s opening Supercars race of the weekend commences at 1355 AEST on Saturday.