LAS VEGAS — Dale Earnhardt Jr. knew he probably didn't have enough fuel to finish. He kept going anyway.
And when Earnhardt's tank went dry on the final lap, Brad Keselowski was there to clean up.
Keselowski surged ahead when Earnhardt ran out of fuel, claiming a dramatic victory in Sunday's NASCAR Sprint Cup Kobalt 400 at Las Vegas Motor Speedway.
Earnhardt's Chevy sputtered and slowed out of Turn 2, and Keselowski roared past on the backstretch in his Penske Ford for the first weekend sweep in his career. Keselowski followed Saturday's Nationwide series victory with his first Las Vegas Cup win, doing it in exhilarating fashion against the friend and mentor who gave him his first big break in racing.
"That's what you live for as a driver, at least I do," Keselowski said. "Those moments where you're side by side and you lay it all out on the racetrack and bring back the car with the tires smoking, engine smoking, and you're worn out inside because you gave it all you had. It was one of those races there at the end."
Keselowski knew all about the fuel shortage faced by Earnhardt and Carl Edwards, who both made their final pit stops about 10 laps before him. So the 2012 Sprint Cup champion forced the issue.
"I felt like we could run him down," Keselowski said of Earnhardt. "He was going to have to burn fuel to keep me behind him. At that point, it was just a matter of whether a yellow (flag) came out or not, because it was just a ticking time bomb. It worked in our favor today."
Keselowski got his big break and first full-time ride in NASCAR when Earnhardt picked him to drive for his Nationwide team in 2007.
On Sunday, Earnhardt finished second and didn't regret it, secure in his overall position thanks to the new rules in the Chase for the Championship, which puts increased emphasis on wins. Still, his Hendrick Motorsports Chevy was just a few ounces of fuel shy of earning him a second victory in three races to start the season.
When Earnhardt sat down for his postrace news conference in front of two cans of his sponsor's energy drink, he picked up one can wistfully: "That's all we needed, just 16 ounces."
The Daytona 500 champion was disappointed but not discouraged after his spectacular start to the season. He also finished second last week at Phoenix.
"We weren't supposed to make it," he said. "We were trying to save as much as we can and make it work, but we knew we were short. We wouldn't have finished second if we didn't have that strategy."
Earnhardt also praised NASCAR's new Chase setup, which let him take a fuel gamble because his Daytona 500 all but sealed his spot.
"I think the new format definitely is showing it has tons of positives," Earnhardt said. "It's better as far as entertainment for our sport."
With his wife due to give birth at any minute, Paul Menard finished third, in front of Keselowski's teammate, pole-sitter Joey Logano. Edwards was fifth.
Note: Chip Ganassi Racing signed Dylan Kwasniewski, 18, as a development driver, making the announcement at Kwasniewski's hometown track. Kwasniewski is in his first full-time Nationwide series season with Turner Scott Motorsports.