JOLIET, Ill. — Although there will be floodlights all around the track, NASCAR teams still are very much in the dark going into the first Sprint Cup series night race at Chicagoland Speedway.

After seven years of racing at the 1.5-mile track on the outskirts of suburban Chicago during the daytime, the race was moved to Saturday night this season.

But NASCAR threw its teams a curveball by not scheduling any nighttime practice sessions at the track in the two days leading up to Saturday's race. And Thursday night's qualifying session was rained out, meaning the first time many drivers will see the track under the lights will be when they take the green flag.

Add in NASCAR's new Car of Tomorrow, which is being used at Chicagoland for the first time after it appeared only in selected races last season, and Sprint Cup series champion Jimmie Johnson says teams are doing a "large degree" of speculating on how to properly adjust their cars to make them handle properly.

"There is a lot of guessing going on," Johnson said. "And engineers are working hard with the crew chief to dream up the optimum setup."

Teams usually keep meticulous notebooks of information on which suspension settings seem to work best in different conditions at each track. But Johnson's teammate, Jeff Gordon, said Hendrick Motorsports' book on Chicagoland won't be of much help this weekend.

"There is no comparison because we've never run here with this car before," Gordon said. "So all the notes and everything that we've learned from the past is pretty much out the window. Other than knowing where the bumps and dips are, it's all new for us."

Johnson said it would be a lot like the 600-mile race at Lowe's Motor Speedway, where teams begin racing in the daylight and end up under the lights.

"As time goes on, we just learn how to adjust and anticipate what things will be like," Johnson said. "I would assume that a lot of guys will have the philosophy that you would in the 600-mile race that we have and the track changing and having spring rubbers and a lot of adjustments that you can change quickly on a pit stop built into the cars. But we're all learning."

Several Cup stars were in Friday night's Nationwide series race, hoping a warm-up race under the lights would teach them a thing or two that they could apply to Saturday. Among the big names racing Friday were Tony Stewart, Kevin Harvick, Jeff Burton, Clint Bowyer, Kyle Busch, Carl Edwards, Matt Kenseth and Greg Biffle.

"Fortunately I'm in the Nationwide race, that's what helps out a lot of us guys," Busch said.

Dale Earnhardt Jr. said the track already was becoming easier to pass on with age, as cars stick better to broken-in pavement. Racing at night could make for an even grippier track, making passing easier.

"I like it," Earnhardt said. "This track is aging and turning gray and losing grip. So at night, it will bring in some grip. But since the track has aged, you will still be able to move around on it. It will be kind of fun."

"I really like this track. It has got some bumps and stuff that are getting worse and worse in turn 3, but it is still a fun track."

The lights will change the way drivers approach the track, too. Sometimes, Gordon said, it's actually better.

"I am anxious to see this track under the lights," Gordon said. "You're always curious how they have lit the track and what kind of shadows and glares there are. Usually it's better at night than it is during the day. And I'm sure the conditions will certainly be really good because you want to race under cool track conditions and it makes the cars handle better and faster and I think it makes for a more exciting race."

Johnson agreed.

"When you're out there, I can see how this track has aged," Johnson said. "And I really think we're going to see the best race that this track has ever had this weekend."