Chase Elliott has become the youngest champion in NASCAR history by wrapping up the Nationwide Series title Saturday at Phoenix International Raceway.

The 18-year-old rookie is the youngest driver to win a title in any of NASCAR's three national series.

He clinched the championship for JR Motorsports with a fifth-place finish at Phoenix. His official celebration will have to wait until next week's season finale at Homestead-Miami Speedway.

Brad Keselowski won the race with a pass of Kyle Busch following a restart on the two-lap overtime sprint to the finish. Busch led 187 of the 206 laps but was denied the victory because Keselowski was given the final chance to catch him after a caution with one lap remaining in regulation.