Saturday practices are supposed to give teams opportunities to fine-tune their cars for Sunday's race, but for Marcos Ambrose, the first session at Infineon Raceway brought an unwelcome calamity.

Ambrose, who qualified third Friday, was leading practice and working on enhancements to his car's handling when the engine in his #47 Toyota exploded 25 minutes into the session. Forced to change engines, Ambrose must start from the rear of the field in Sunday's Toyota/Save Mart 350.

"It blew up pretty good," Ambrose said ruefully.

Though Ambrose knows that starting from the back will substantially diminish his chances of winning his first Sprint Cup race, he was philosophical.

"I came from dead last at Watkins Glen (last year) to finish third, so it can be done," Ambrose said. "We'll have to make some gambles on fuel strategy to get up there.

"There was no warning - the motor just blew. 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 setup 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's words proved to be prophetic - on Saturday. After his team changed the engine, the Australian driver returned to the track for two laps in final practice and got into the back of Jimmie Johnson's #48 Chevrolet entering turn eleven on the second of his two laps. The cars made contact twice, tearing the bumper cover of Johnson's car from the junction with the left rear quarter panel.

"It was my fault - the second lap on the track and I'm just trying to get a lap time on the board to see what we could do," Ambrose said. "I outbraked myself a little bit, bumped Jimmie and he just aborted the lap and couldn't get going. I just thought that he was going to move on, and I ran into him again.

"You know, I don't want to knock into Jimmie Johnson. He's a three-time champion. He's owns the racetrack - I'm just borrowing it off him from time to time. I'll go and talk to him this afternoon, make sure things are all right, make sure he knows that I didn't mean to bump into him."

The damage to Johnson's Chevy was superficial and will not force him to a backup car. Johnson attended a team debriefing session after practice and was not available for comment.

by Reid Spencer/Sporting News