Paul Dumbrell has burst out of the blocks at the Sandown 500, scorching his way around the Melbourne circuit to chart a new practice lap record.

The Bathurst 1000 champion and two-time development series winner showed terrific pace to lower the benchmark to 1:07.8467 on Friday morning, stealing the record from his co-driver Jamie Whincup.

By the end of the weekend’s opening practice session, five cars had all dipped under Whincup’s practice record set in 2014.

But the rest of the field was at least four tenths of a second behind the Triple Eight Commodore, marking car No.1 as the one to beat in the opening race of the 2018 Enduro series.

A beaming Dumbrell said the combination of well-balanced cars and a quick track wouldn’t count for much on Saturday, when up to 10mm of rain is forecast.

“The track is great today but it will be diabolical tomorrow,” he laughed.

Sunday’s 500-kilometre classic comes before next month’s Bathurst 1000 and the Gold Coast 600 as the defining races of the Supercars series.

In the drivers championship, Scott McLaughlin sits just 19 points behind leader Shane van Gisbergen, with a major gulf to Whincup in third.

McLaughlin’s co-driver Alex Premat finished seventh in the opening practice session of the weekend, 0.74 seconds behind Dumbrell.

Well credentialed Kiwi Earl Bamber, who has been drafted in to accompany van Gisbergen, charted 1:08.7871 to finish 14th.

Two Nissans finished in the top four, with Dean Fiore second and 18-year-old Alex Rullo in fourth.

Qualifying for the long-distance race takes place on Saturday before Sunday’s race begins at 1.20pm.