AVONDALE, Ariz. -- Rookie Kyle Busch outdrove NASCAR's top contenders to win Sunday.

All but one, that is.

"I just want to say I'm behind my brother 100 percent," the 20-year-old winner said of Kurt Busch, who was suspended earlier in the day for a Friday night run-in with police.

Standing on top of his No. 5 Chevrolet and waving to the cheering crowd at Phoenix International Raceway, Busch called his older brother, who won last year's Nextel Cup, "a true champion."

Title contender Greg Biffle dominated the race, leading 189 of 312 laps in the Checker Auto Parts 500. But the younger Busch, who drives for Hendrick Motorsports, used a pit stop strategy to get track position, taking the lead for the first time on Lap 230 by staying on track when the leaders pitted.  More