Marcos Ambrose will drop to the back of the grid after blowing up an engine during the final practice session for Sunday's NASCAR Sprint Cup Series race at Infineon Raceway.
The Australian led both the first and second practice sessions of the weekend, but as he was about to start his second run during the third and final practice, the engine on his car blew up.
The JTG Daugherty Racing driver was set to start the race from third on the grid, but being forced to change the engine on his No. 47 Toyota will send him to the back of the field, effectively costing him his best ever qualifying result in the Sprint Cup series.
"There was no warning -- the motor just blew," said Ambrose. "Everything was fine and then it just blew up. It was perfect up until then. We had good horsepower, and we have been dominant all weekend.
"This puts us in the back, but we have a never-give-up attitude. We'll have to have a different strategy and set up for Sunday.
"We know we still have a great chance to win. We may have to put a fender to some to get there, but you have to pick your moments. Everyone you run into, you have to expect them to get you back."
Ambrose then had an incident with Jimmie Johnson at the end of the session when he went out to complete a couple of laps with a new engine. The Australian, who admitted blame afterwards, got into the back of Johnson when he outbraked himself into the final turn, causing some bodywork damage to both cars.
Also starting from the back of the grid will be Scott Speed, who had failed to make the field for Sunday's race during qualifying. However, for the second time this season, his team was able to put a deal in place for the Californian to drive Joe Nemechek's No. 87 car, allowing him to make his road course debut in the series.
David Gilliland, who finished second at Sonoma last year, will also drop to the back after crashing his car during practice in a silly incident while leaving pit road behind John Andretti. His TRG team leased Martin Truex's back up car, which Gilliland will race on Sunday.
"Our racecar was really good, the best I have ever had for this race," said Gilliland. "That car was purchased from Earnhardt Ganassi so the one we will race should be relatively the same.
"The guys are working really hard to get the car ready and I will work just as hard on the track tomorrow to work my up through the field from back. I am ready to turn this into a positive."
In another exchange between teams, Wood Brothers will put his pitcrew to Boris Said's service, as the road course specialist will be the highest starting Ford in the field.
AJ Allmendinger was fastest in the final practice session, ahead of Ron Fellows, Robby Gordon, Juan Pablo Montoya and Kasey Kahne.