Chaz Mostert has has finished on top of Practice 1 for the Beaurepaires Melbourne 400 by a healthy 0.4s margin, having used new tyres at the end.

Mostert leapt up from 18th in the final two minutes of the 30-minute session with a 1:55.5743s in the Supercheap Auto Mustang.

Anton De Pasquale ended up second from Jamie Whincup (Red Bull HRT ZB Commodore), Mark Winterbottom (Irwin ZB Commodore), and the second Tickford Mustang of Lee Holdsworth, while Virgin Australia Supercars Championship leader Scott McLaughlin was shuffled back to eighth.

Mostert’s, however, was not a trouble-free session and he also confirmed that he used a new tyre to set his lap time.

“Session was pretty tough for us,” he revealed.

“We had a little comm(unications) issue so couldn’t really hear what Adam (de Borre, engineer) was saying and couldn’t relay what I needed back from the car.

“Obviously putting a green tyre on there at the end it really showed some pace in the car but probably a little bit of tuning up to do.

“Probably a qualifying car it was pretty good, which was nice to be in Practice 1, but no doubt there will be a lot of other quick guys coming for us in the next one.”

McLaughlin had held top spot for much of the session in the #17 Shell V-Power Mustang with a 1:56.6542s on his second flyer.

With the Kiwi having gone no quicker thereafter, Scott Pye took over the lead for a handful of seconds before Whincup put just over half a second between himself and the rest of the field with a 1:56.0824s.

Mostert then bettered Whincup’s lap by almost the same margin, before De Pasquale split them shortly after in the #99 Penrite ZB Commodore at 0.4299s off the pace.

Winterbottom jumped from 19th to fourth with the chequered flag out, 0.6305s away from Mostert and only 0.0046s faster than the man with whom he effectively swapped seats, Holdsworth (The Bottle-O Racing).

James Courtney ended up best of the Mobil 1 Mega ZB Commodores at one position and just over a tenth of a second faster than Pye.

Behind them and McLaughlin was Cameron Waters (Monster Energy Mustang), while Simona De Silvestro (Harvey Norman Altima) improved after the chequered flag to be best of the Kelly Racing entries in 10th, bumping Richie Stanaway (Boost Mobile ZB Commodore) out of the top 10.

Both Shane van Gisbergen’s and Nick Percat’s ZB Commodores were afflicted by splitter flap.

The former did not set a fully representative time and ended up all the way back in 22nd position in the #97 Triple Eight entry, while Percat managed to get back out and drag a 1:57.1286s from the #8 Freightliner BJR car which put it 13th.

Will Davison, meanwhile, took 12th after the Milwaukee Mustang had to have an oil cooler line replaced.

Fabian Coulthard (DJR Team Penske Mustang) was 14th and David Reynolds (Erebus ZB Commodore) 16th.

Practice 2, another half-hour session, starts today at 1500 local time/AEDT.

Results: Practice 1