A week before they were to race for the NASCAR Sprint Series championship at Homestead-Miami Speedway, Jimmie Johnson and Kyle Busch sat side-by-side at the dais in the Phoenix International Raceway media center and began the bickering that invariably accompanies the battle for the series title.

“I think my stats at Homestead show that I’m the favorite, right?” Johnson said facetiously.

“I think my results from last year show that I’m the favorite, right?” Busch retorted.

Busch goes to Homestead as the defending champion, having overcome a broken leg and foot that caused him to miss the first 11 races of the 2015 season. With the elimination of Kevin Harvick in Sunday’s Can-Am 500 at Phoenix, Busch is the only Championship 4 contender who has won a title under the 16-driver Chase format introduced by NASCAR in 2014.

Johnson, on the other hand, is a six-time champion, and having won at Martinsville in the first race of the Chase’s Round of 8, he and crew chief Chad Knaus will have had three weeks to prepare for the season finale.

“In a couple weeks we didn't have a chance to build a new car, but we've got some stuff in the pipeline and a couple cars to choose from,” Johnson said of his preparations for Sunday’s race (2:30 p.m. ET on NBC). “Yes, we have had the luxury of a few weeks of time, but a lot of these decisions are made so far in advance—which cars, and getting them approved through NASCAR—that the advantage doesn't come there.

“I think it's more in preparation, digging through notes, watching videos, just being prepared. I think that's where a small advantage may come from, and we'll see if we can take advantage of that.”

Busch, on the other hand, didn’t know he’d have a chance to defend his title until the final lap of the second overtime at Phoenix, where he ran second to fellow Championship 4 contender Joey Logano.

To say Busch made the final four by the skin of his teeth is an understatement. Throughout most of Sunday’s race, he ran outside the top 10, and it wasn’t until he gained track position through a series of banzai moves on a late restart that Busch’s car came to life.

Tempering Busch’s satisfaction at qualifying for the Championship 4 was ambivalence about a late wreck that involving Busch, Alex Bowman and then-race-leader Matt Kenseth (Busch’s Joe Gibbs Racing teammate) that knocked Kenseth out of the championship picture.

“That was a really ugly race for us,” Busch said. “We ran pretty bad all day, and the closer we got to the front the better we got, but that still doesn’t ... it was a great finish for us but we hoped it could be a little better than that.”

Despite Kenseth’s unceremonious exit, Busch is the only driver with a teammate in the Championship 4. After a hard crash at Martinsville, Carl Edwards resurrected his championship hopes with a victory in the rain-shortened AAA Texas 500 at Texas Motor Speedway.

And the prospect of teammates racing each other for a title provided another opening for Johnson, who has faced that problem on multiple occasions at Hendrick Motorsports.

“It sucks,” Johnson told Busch. “You’re going to have a miserable time down there.”

But who really has an edge? A six-time champion, a defending champion, or a pair of drivers hungry for a first championship?

Here’s a primer on the Championship 4: