CONCORD, N.C. -- Kurt Busch said early in the week that younger brother Kyle questioned if he was taking this racing business as seriously as a championship contender should.
Kurt assured him he was.
Anybody who doubted that should have seen the emotion on Busch's face as he celebrated Sunday night's victory in the Coca-Cola 600 at Charlotte Motor Speedway, his second win in a week at the 1.5-mile track in the heart of NASCAR country.
They should have heard the exhilaration in his voice as he talked about going to Victory Lane at a track where he'd never had a top-10 before this season in a race that team owner Roger Penske had never won, about keeping runner-up Jamie McMurray from giving owner Chip Ganassi a monumental Indianapolis 500-Coke 600 sweep.
It was raw.
It was honest.
"I'm speechless that we swept both races," said Busch, who won the Sprint All-Star Race eight days earlier.
Yes, Busch is serious about what he does. He has to be considered a serious threat to succeed four-time defending Sprint Cup champion Jimmie Johnson as well.
The win was his second in a points race this season and third overall. It vaulted him past Johnson into sixth in points at the halfway point of the regular season.
There's a swagger about Busch and crew chief Steve Addington that leads us to believe they can keep this up, as Busch did in 2004 when he won the inaugural Chase at Roush Fenway Racing.
Just because Busch doesn't take losing as hard as his brother doesn't mean he doesn't want to win just as much. He learned back in 2003 that beating your head against the wall doesn't make the race team better, and proved that with a renewed attitude during his championship season.
Since then he really hasn't had a car or team capable of being a championship contender. Now he does.
Even Kyle admits his brother is a threat.
"I don't see why not," Kyle said after finishing third. "He's been running well all year long. The team is doing well."
Busch was so good early on Saturday night it scared him. He was afraid if his car handled that well in the daylight that maybe it would change for the worse at night. Instead, it got better.
Were it not for McMurray, whose car got better as day turned into night, it wouldn't have been a contest. Were it not for Busch's pit crew getting him out ahead of McMurray on the final stop, we may be talking about Ganassi having the single-biggest day of a motorsports owner.
Despite having a car so dominant that it led 252 of 400 laps, a lot still had to go right for Busch to win. None was more important than the set of red-rimmed wheels Addington got from Penske Racing teammate Sam Hornish Jr.'s team to give the car just the right balance at the end.
"This was a race for the ages," Busch said.
It was eight days for the ages for Busch. It began with winning the pole for the All-Star Race because qualifying was rained out, continued with the win in the non-points event that appeared to be Johnson's and then Hamlin's or Busch's to win during the first three segments.
It continued with a near-pole run for the 600 on Thursday and ended with a victory at a track where Busch's average finish had been 20.9.
It was as close to perfect as a driver could ask, "a dream come true," as Busch called it.
I'm speechless that we swept both races. ... This was a race for the ages.
”-- Kurt Busch
Could it propel him to a title? We won't know that for another six months. But the trust Busch put in Addington to come up with a setup so radical that Addington called it a "science project" and the chemistry the two are developing seem special.
Busch was so jacked that he plans to have special rings made up for everyone on the team commemorating the Charlotte Sweep.
"As long as we're getting better, that's the big key," Addington said.
This racing business also is serious for Addington, who was fired as Kyle's crew chief near the end of last season. You could hear it in his voice as he shouted over his radio as Kurt took the checkered flag.
"Hell yeah!" Addington said. "That's what I'm talking about. Kurt, that was awesome! That was freaking awesome! I have never seen anybody drive a race car and be as smooth as you were."
Replied Busch, "You are the man, Steve."
Together they are the team right now. That could change as the season wears on. Remember, Johnson won the first five races and now he's finished 31st or worse in three of the last five races after a crash left him 37th on Saturday.
"They're going to be a championship contender," Addington assured of Johnson's team. "If you're going to win this championship, you're going to have to beat those guys and you're going to have to beat the Gibbs bunch and Hendrick bunch."
You're going to have to beat the older Busch brother as well.
He's serious about winning even though he doesn't always show it.
"I'm not one to go out there with a big flash and a big flair," Busch said. "I used to early on. I'd run my head up against the wall. I'd run my race car up against the wall. Reviews came in negative.
"For me, that's not how I wanted to be remembered, how I wanted to be looked at sitting there on the porch talking with my grandkids about things."
He wants to be remembered as a champion, and you can't do that without being serious.
David Newton covers NASCAR for ESPN.com. He can be reached at email@example.com.