MARTINSVILLE -- Jeff Burton pulled into his garage stall, his engine gone south on a weekend that never really got turned in the right direction.

Team members circled the car, lifted the hood and searched for the answers. A broken valve train on lap 217 of the 500-lap Subway 500 at Martinsville Speedway on Sunday ended Burton's day and sent the South Boston driver tumbling from first to fifth in the points standings.

But when Burton's car sputtered into the garage area, there was still work to be done.

Crew members clad in orange pushed the machine in reverse out of its garage stall. They ran behind the car again, once again pointing in the right direction in one last effort to get the engine refired. But the motor had quit for good.

But there was no-quit in Burton's bunch.

"We're a team. We fight together. We die together," said Burton, who entered the race with a 45-point lead but left 48 points behind new leader Matt Kenseth. "We do everything together and that's what it's all about."

Burton's struggles began during Friday's qualifying when his Chevrolet posted only the 28th fastest lap.

Starting deep in the field Sunday, Burton made little progress.

On lap 106, leader Jeff Gordon put Burton a lap down.

Still struggling to move forward, Burton drove to the inside on lap 213 and lost multiple positions.

Burton stayed on the track, hoping the problem would go away. It didn't. Four laps later, he was parked in the garage. In that instant, fellow Chase contenders knew this was their chance to make up some precious ground in the standings.

"I think I was right beside him when his motor did go," said second-place finisher Denny Hamlin. "I asked the crew, 'what's the status on the 31?' ''

Prior to Sunday, Burton's Chase status was coveted, but not perfect.

Tire problems late at Talladega relegated Burton to a 27th-place finish two weeks ago. In the other four races since the Chase began at New Hampshire in September, Burton had finished no worse than seventh.

Burton, while confident in both his driving abilities and team, wasn't banking on his string of strong finishes to continue.

"Everybody has had an issue in this Chase and we had ours today," Burton said. "This thing is not over by any means."

Sunday's outcome certainly proved it. Dale Earnhardt Jr., who ran inside the top 10 for most of the day and stood to leave Martinsville no worse than third in the standings, spun late after careening off Kasey Kahne.

Jimmie Johnson, whose title hopes appeared in serious jeopardy early in the Chase, is now third, just 41 points behind Kenseth after winning Sunday.

Burton's Richard Childress Racing teammate, Kevin Harvick struggled during portions of the race and finished ninth.

"I hate that the No. 31 had trouble," Harvick said, "cause at the end of this thing we need to be one-two somehow or another."

Burton's descent in the standings marks the first time that the points lead has changed hands in the second half of the Chase since its inception in 2004.

With the points separation so close, it's likely to change again.

"Just a bad day for us but we won't quit," Burton said. "I guarantee that. This team is really tough and really resilient."