Champion elect Jamie Whincup has started strong at the Sydney NRMA 500, shooting to the top of the times with a 1min28.939.
Red Bull's Whincup was just 0.01sec quicker than TEKNO's quick Kiwi Shane van Gisbergen, who missed the majority of the session due to a reported power steering issue -but managed to emerge from the pits with five minutes to go and generate a quick lap.
Michael Caruso in the Norton Nissan was third, with a 1min29.279.
Man of the moment Marcos Ambrose got through the session unscathed, a huge lock up late in the session showing he was pushing his XBOX racer around the street circuit. His best time, leaving him 23rd of 26 cars, was a 1min30.336, 1.396sec adrift of Whincup.
Ambrose, returning after nine years overseas, has never before contested the Sydney street circuit or raced a new generation V8 Supercar.
Fourth was Jason Bright, with Fabian Coulthard, Scott Pye, James Courtney, Garth Tander, Tim Slade and David Reynolds completing the top 10.
Others to note include Scott McLaughlin in 12th, Chaz Mostert 13th, Craig Lowndes 15th and Mark Winterbottom 18th.
Two more 20-minute practice sessions remain today, with a final fourth practice tomorrow morning.