Lowndes in doubt for opener

Holden star Craig Lowndes is today's crasher who is least likely to make the start of the first 125km race at the NRMA Sydney 500 this afternoon.

Wildcard Marcos Ambrose seems certain to be on the grid for the race, as does Erebus Motorsport V8's Lee Holdsworth.

Holdsworth crashed in this morning's final practice session at Sydney Olympic Park after the power steering failed in his Mercedes-Benz E63 AMG.

Both Lowndes and Ambrose hit the wall at turn five after making driving errors in the first qualifying session.

"I missed a shift and it just got away from me," revealed Ambrose, who is making his first V8 Supercars start in nine years in the Xbox Ford Falcon FG II being run by Dick Johnson Racing.

Lowndes clipped the wall on the inside of the turn on his fastest lap and ricocheted into the outside wall at high speed in his Red Bull Racing Australia Holden Commodore VF.

The impact damage was severe enough for the team to change the car's transaxle. Asked if the car would make the start of the first race at 2.30pm, team manager Mark Dutton would only say: "It will be tight".

Lowndes qualified 20th for today's first race, which starts at 2.30pm, and Ambrose 24th. Holdsworth will start from the back of the grid. They will be off the last three spots on the grid for the second race, which starts at 4.30pm.