Busch slipped into the lead when leader Jeff Gordon and Elliott Sadler scuffled battling for the top spot on lap 271 .
Busch started last in the field after losing an engine in Saturday 's Happy Hour practice session .
Busch , who started last in the field after losing an engine in Saturday 's Happy Hour practice session , slipped into the lead when leader Jeff Gordon and Elliott Sadler scuffled battling for the top spot on lap 271 .