MARTINSVILLE -- It's the four-letter word of racing.

Luck.

It's why Jeff Burton leads the points and Jeff Gordon doesn't. Why an engine breaks and another doesn't. Why a car crashes and another doesn't. Or so drivers say.

Most drivers state that luck shapes this championship run.

Don't believe it?

Former champ Kurt Busch does.

"There's something out there that helps teams win championships," said Busch, who won the pole for Sunday's Subway 500 at Martinsville Speedway.

He's not talking about fast cars and good pit strategy.

Busch won the 2004 title after a few spins during the Chase and a wheel sliding off in the season finale. Younger brother Kyle tried to channel that fortune but failed.

"I've tried different socks, I've tried different underwear, I've tried different T-shirts, it doesn't matter," he says.

Maybe he's trying too hard.

Luck plays a certain role but it seems to have become a crutch or a joke among the drivers to see how many times they can mention it. Most did Friday. Luck is needed in any endeavor, but whether it dictates a result as much as some drivers suggest is debatable.

Then again.

Some drivers in the title Chase are leery about Sunday's race. Forty-three cars packed onto a .526-mile track leave little room to hide from trouble. Some drivers look at this as the final wild-card race where they have a greater chance of being involved in an accident not of their doing compared to other tracks.

Burton, who leads the points, recognizes his fortune could change Sunday.

"We've put pressure on everybody by running well, but we haven't had as much bad luck as the other guys have," he says. "That's the reality."

Burton's only problem came at Talladega, when he suffered a flat tire with about 10 laps left and finished 27th. The result hurt, but it could have been worse with Dale Earnhardt Jr. and Jimmie Johnson running first and second on the last lap. Brian Vickers tapped Johnson, causing Johnson and Earnhardt to crash. Both were about to gain 80 points on Burton. Instead, they each gained less than 20 points.

Kasey Kahne calls that luck and says it has been key in Burton leading the points.

"He's had great luck," Kahne said of Burton. "The way this season has gone, I feel luck is all over this place."

Kahne often has had bad luck. At least until he won last week's Bank of America 500 in Charlotte.

Gordon isn't convinced that bad luck caused a piston to fail and his engine to blow at Charlotte, a fuel pump to break at Kansas or a wreck in front of him at Talladega to damage his car.

"I've always said that I'm a big believer that you make a lot of your luck," Gordon says. "I think that there are silly things that just happen that you could blame on luck or whatever you want."

Maybe. It hasn't taken rookie Denny Hamlin long to sound like a veteran. Hamlin avoided most accidents in the first 26 races and used consistent finishes to make the Chase.

He's suffered various problems since. His car was damaged in two crashes at Talladega, one after a pit gamble put the team back in the pack and put Hamlin in greater danger of such a scenario. Also, a first-lap crash at Charlotte collected Hamlin.

"We've been running well, we just really had three weeks of bad luck," Hamlin says. "Luckily, we had good enough runs the first couple of races in the Chase that countered it."

Any more doubts? Consider what Kevin Harvick, who has won two Busch crowns, says.

"It is going to come down to who makes it happen," he says, "who has good luck."