Ever since NASCAR implemented its current provision for overtime racing, late-race aggression has been on the rise. In fact, each of this year's three races has ended in a green-white-checkered finish, as the overtime periods are called.
"Everybody's just digging for every spot they can out there," said Greg Biffle, who survived Sunday's late-race madness at Las Vegas Motor Speedway for an eighth-place finish.
One overtime period is mandated when the regulation is slated to end under a yellow caution flag because of a wreck or debris on the racetrack.
At that point, NASCAR cleans up the track; throws the green flag to restart the race; and, on the next lap, throws the white flag to signal the last lap of the race. Drivers finish under the checkered.
The mandate was implemented in July 2004 after negative fan reaction to several yellow-flag finishes, including Jeff Gordon's win over Dale Earnhardt Jr. under caution at Talladega. Fans pelted Gordon's car with debris as he crept around the 2.66-mile superspeedway for the last lap.
"The green-white-checkered format is an attempt to achieve everyone's goals -- a green-flag finish," NASCAR President Mike Helton said at the time. "This format has been successful in the NASCAR Craftsman Truck Series, and considering the tight competition week in and week out in the other two national series, we feel the time is right to use the same procedure in all three national series."
When Matt Kenseth, who was leading late in the Las Vegas race Sunday, saw the caution come out to set up a green-white-checkered, he was frustrated.
He was leading two weekends ago at California when another green-white-checker was set up, and he did everything he could to hold off Jimmie Johnson to prevail. This time, he worried that he didn't have enough left in his car and questioned whether the caution was necessary.
"That was my first reaction, just because if you're the leader and they throw a caution [when] there's two to go and there's going to be a green-white-checkered, that's going to be your reaction," he said.
At first, Kenseth didn't know what brought out the caution, but once he saw debris he was soothed a bit. But only a bit.
"I knew [when they set up] that green-white-checkered, we would probably be in trouble because [Johnson] was a lot faster than me when they threw the caution," Kenseth said.
Johnson's teammates felt the same way.
"If you give Jimmie a green-white-checkered," Kyle Busch said, "and he's in first or second, he's going to put on a whale of a show for us, and he ended up doing that today."
Johnson stuck the nose of his No. 48 Chevy on the outside of Kenseth's No. 17 Ford and passed Kenseth in the last turn.
Not surprisingly, Johnson is a fan of the overtime periods.
"I personally feel that the green-white-checkered is a great compromise," he said. "If I was a paying fan and sat in the grandstands and the race ended under caution, I'd be upset. I think one attempt at a green-white-finish for the competition side and for the fans [is good]."
But Johnson admitted that the green-white-checkered finish did change the outcome of the race.
"I don't think I would have caught Matt Kenseth," he said. "I was slowly catching him. If we'd have had a long run, I think I could have been up there racing with him. But if it stayed green, I believe Matt had it in the bag. When the caution came out, I could get right on his bumper and could work out my game plan from there."
Although most drivers agree that racing has gotten more aggressive of late, not all agree that the overtime rule has caused it.
The concern is that because a green-white-checkered can change the complexion of a race, it necessarily will change a driver's approach to the last few laps. Those at the head of the pack won't do anything crazy to bring out a caution, but they will try harder to pass. The focus of more concern is the increased aggression toward the middle of the pack among those trying to get into the top 10.
"When you're that close at the end, all the sensible thinking is gone and you do all you can to win the race," Johnson said, speaking from a race leader's perspective.
"It gets real dicey," said Dale Jarrett, who was in the middle of the pack in Vegas.
There's an underlying question of cause and effect, and whether the overtime period is the cause of the perceived aggression or the overtime was necessary because of the perception of increased aggression is hotly debated.
For the leaders in any particular race, though, it makes for nerve-racking finishes.
"As soon as that caution came out, I was actually kind of frustrated," said Busch, who finished third. "I was like, man, couldn't we just finish this thing?"
Rupen Fofaria is a regular contributor to ESPN.com. He can be reached at firstname.lastname@example.org.