Why NASCAR’s Kobalt Tools 500 could hold surprises

Carl Edwards and Tony Stewart are now the focus of NASCAR’s Chase for the Sprint Cup title, but they’re forced to share center stage this weekend with a mile of pavement in the Arizona desert.

Phoenix International Raceway, site of Sunday’s penultimate event in the 10-race Chase playoff, has been repaved and reconfigured, and all of NASCAR seems unsure about what type of race the changes will produce even though teams tested there a month ago.

“Wild card doesn’t start to describe” how the Kobalt Tools 500 will fit into the Chase scenario, said driver Brad Keselowski, a Chase contender who is fifth in the standings.

Edwards has a three-point lead over the red-hot Stewart, who has won the last two races and four of the eight Chase races so far. Kevin Harvick is third, 33 points behind; Matt Kenseth trails by 38 and Keselowski by 49.

With only Phoenix and the season finale at Homestead-Miami (Fla.) Speedway left on the schedule, the Chase is now seen as mainly a battle between Edwards and Stewart.

But the unpredictability of the Phoenix track, which sold out its 56,000 grandstand seats for this race, could lead to surprises.

Edwards, the Roush Fenway Racing driver seeking his first Cup championship, won the fall Phoenix race a year ago. But that’s of little value because of the track’s changes. Instead, “Phoenix is a really big unknown,” Edwards said.

The 47-year-old Phoenix track already was unique because the oval layout had a slight dogleg in the back straightaway. Now, the track has been resurfaced, the dogleg was pushed out a bit and slightly more banking was added to the turns.

The goal, among others, was to promote more side-by-side racing, but drivers said initially there might be only one groove “rubbered in,” leading to suggestions there could be mostly single-file racing Sunday.

The raceway’s keepers in recent weeks have tried to develop a second groove, partly by using a machine that drags tires over the pavement, but it’s unclear how well the tactic will work.

“If the second groove doesn’t come in, it will be a track-position game with a lot of wrecks” as drivers try to muscle their way past others in the single groove, Harvick warned.

To complicate matters further, there’s a possibility of rain in Phoenix this weekend that could wash away some of the rubber that’s been building up on the track.

“If we do not get that [second] groove widened out then it makes for very tricky conditions,” said four-time champion Jeff Gordon, who is eighth in this year’s Chase and won the last race on the Phoenix track’s old surface in February.

Gordon said the new track is compelling not only because it could affect this race’s outcome “but what it does for the championship, because it could shake things up in a big way.”

james.peltz@latimes.com