It was a rough day for Toyota's motor program. For separate reasons, two of Toyota's top drivers - Kyle Busch and Denny Hamlin - had to start at the back of the field for Sunday's Subway Fresh Fit 500 because of motor replacements.
Both situations involved valve springs, which are routinely replaced between qualifying and the race in Sprint Cup. In Hamlin's case, the mechanics found a part failure that required replacing the engine. With Busch, who won Saturday's Nationwide event, human error in re-assembling the engine caused the replacement.
Based on qualifying, Busch would have started fourth and Hamlin eighth. Those were two of Toyota's top three entries, behind pole-sitter Mark Martin.
Busch couldn't finish last week's Daytona 500 due to engine trouble.
The relationship between Busch and Toyota Racing Development has been touchy in the past. Last October, Busch led most of the race in Dover, Del., only to miss a win because he had to pit for gas.
After that race, Busch made critical remarks about TRD over his in-car radio. After the remarks became public, Busch issued an apology to TRD, saying his comments were out of "frustration'' and "very misguided.''
Two other cars also went to the back of the field - David Stremme's Toyota for a transmission problem and Kurt Busch's Chevrolet; he went to a backup car.
FIVE KEY MOMENTS
1. Mark Martin, the pole winner and clearly the strongest car at the outset of the race, tried early on to just take two tires rather than four. The calculated risk didn't work, and Martin had to enter the pits on green. A caution just after he got to his pit mitigated the time he was about to lose.
2. Danica Patrick's crash with a little over 100 laps left gave everyone else the pit stop they needed in anticipation of a long green-flag run. That's right about when Carl Edwards establish his dominance as Sunday's car to beat.
3. With about 40 laps left, drivers and crews for the challengers started doing their balancing act between conserving fuel and not losing track position. Jimmie Johnson let up for a few laps, allowing Brad Keselowski to pass him out of concern for his fuel situation. A back-and-forth between Johnson and Keselowski could only work in Edwards' favor down the stretch.
4. Ken Schrader tapping the wall with three laps left brought out the caution, setting up the spectacular green-white-checker finish. Barring that, Edwards would have won going away.
5. In the restart, Edwards didn't quite keep up with the speed of the pace car, which Johnson said breaks NASCAR protocol. Of that bending of the rules - it causes the pursuit to lose cadence with the leader -- Denny Hamlin said, "I just know Carl was way out there once we got started.''
Kobalt Tools 400
Where: Las Vegas Motor Speedway.
When: 3 p.m. Sunday
Radio: Performance Racing Network
Last year's winner: Tony Stewart