A Saturday morning snow shower at Atlanta Motor Speedway forced NASCAR officials to merge the day's two rounds of practice for Sunday's Kobalt Tools 500 into one session.

When the checkered flag waved over happy hour, Roush Fenway Racing's Greg Biffle stood atop the speed chart.

Biffle, whose fast lap during final practice was 184.229 miles per hour, is concerned about this weekend's tire compound and the limited amount of practice on Saturday.

"It's certainly going to be a crapshoot," Biffle told reporters. "These tires don't have a lot of grip, everybody knows that, but then with the temperature going from 40 degrees to 60 and sunny [on Sunday], the track is going to be tremendously slick.

"It's going to be like a big Darlington. You're going to have to slow down a lot in the corners and feather the gas back through it."

Unadilla's David Ragan, who starts 14th in the 500, downplayed his chances of winning in his home state Sunday.

"As for the long runs, I think we're mediocre at best," he said. "The car just can't find a happy spot. It's either real loose or real tight. We've really tried to change a lot because we know the track is going to be a little different [on Sunday].

"But I never sweat it too bad because we've been horrible on Saturdays and [crew chief] Jimmy [Fennig] is always good for some adjustments on Sunday morning. And 500 miles here in Atlanta is a long race. It's not too great now, but I'm glad we got in [final practice] before we raced."

Drivers on the bubble

Following next weekend's Food City 500 at Bristol, guaranteed starting positions for Sprint Cup Series events go to teams in the top 35 in current car-owner points.

Notable drivers who are presently outside the top 35 include Dave Blaney, Dario Franchitti, Sam Hornish Jr., Regan Smith and Kyle Petty.

A bad outing Sunday could put four-time Cup champion Jeff Gordon, who is 23rd in points, on the top 35 bubble.

"I'm just trying to keep myself in the top 35," Gordon joked Friday night after winning the pole for Sunday's race. "There are some interesting little things going around the garage area right now about who is in the top 35 and who is trying to protect and help other people stay in the top 35.

"You know what? This business has turned into just that. It's big business. And these sponsors pay a lot of money and you can't afford to lose them."

Sophomore driver Paul Menard, who finished 34th in points in 2007, is 26th in owner points through the first three races this year.

"We had a rough rookie season, but most people do," he said. "We started this year off on the right foot."

"We're locked in [the top 35] in owner points and continue to get better each week. Eventually, we'll be up there running with all the big boys in the top 10."

Drivers can't get a grip on new tires

Several Cup drivers, including Robby Gordon, have been critical over the tire that Goodyear has brought to AMS this weekend.

"We're on the edge," Gordon told AMS pit-notes reporter Angela Revell. "It's a handful. We're all sliding all over the place."

Gordon offered a remedy.

"Call Toyo," he said. "T-O-Y-O. It's a company in Japan. Or Firestone."

— Staff writer Rick Minter contributed to this report.