The road to the first Nextel Cup championship may very likely begin this week on a 1½-mile oval of asphalt in Las Vegas.

After nearly two weeks of testing in Daytona earlier this month, NASCAR Nextel Cup and Busch Series teams are shaking out even more winter cobwebs this week at Las Vegas Motor Speedway.

Veteran Jeremy Mayfield led the way in Monday's opening session, topping the speed charts at 170.347 mph (at 31.70 seconds), the only racer to crack the 170 mph barrier. Rookie Kyle Busch, Kurt's younger brother, was second fastest at 169.447 mph (at 31.82 seconds).

Dubbed NASCAR Preseason Thunder Las Vegas, the massive test for all teams is geared primarily for drivers and teams to adjust to new rules this season that affect tires and rear spoilers.

Goodyear has produced a new so-called "soft tire" with a rubber compound designed to wear more evenly under race conditions. As a result, two-tire pit stops likely will be less common in the upcoming season, which should greatly affect and change pit strategy. Full four-tire pit stops will be more common as it will be more difficult for drivers to stretch mileage on the softer tires, which will wear out more quickly. Another advantage to the new tire is it may help to reduce blowouts.

The other significant rule change that is being put into play this week in Sin City is NASCAR's decision to reduce the angle of the rear spoiler on Cup and Busch cars. In so doing, cars will have less downforce, which should slightly increase speeds on straightaways, but also comparatively reduce speeds in turns.

For example, cars may pick up five mph or so on straightaways. But to compensate for that speed gain, drivers will have to brake harder and/or earlier heading into turns. Reducing downforce should also placing more importance on driver skill and decision making rather than allowing drivers to rely primarily on aerodynamics making their cars easier to handle.

Among the drivers who had been looking forward to the Vegas test session are Jeff Gordon and crew chief Robbie Loomis. After finishing fourth in the standings last season -- they were up as high as second for several weeks during the middle of the 2003 campaign -- the brain trust of the No. 24 Chevrolet was eager to see what NASCAR's changes wrought.

"It's going to be an extremely different test," Loomis said during last week's annual NASCAR Media Tour in Charlotte. "It's going to be the first test with the least amount of downforce on the cars than we've had in years, plus Goodyear has a brand new tire for us."

	Gordon is in favor of the changes NASCAR has made.

Loomis said the team will be working on finding a balance in the car, as steps taken to tighten a car up heading into a turn could make the car extremely tight on exit.

"Las Vegas is a racetrack where cars are really tight on the exit of the corner, anyway. We're really just looking for that balance to give Jeff the feel in the race car that he's looking for and give the No. 24 Chevrolet driving well for him all day long."

Gordon has long been a proponent of shaving or dropping the angle of rear spoilers on Cup cars. He advocates minimizing artificial speed reduction devices such as rear spoilers to bring back more control and passing ability behind the wheel for drivers.

"I know (the new rules) made a difference (during testing earlier this month) at Daytona," Gordon said. "That's all I can judge off of. (Teammate) Brian Vickers tested last week at Rockingham and said it was different there, too. I don't think there's enough downforce taken off the cars yet, and so I don't know if we've got the tires in position to fall off as much as I'd like to see them."

But this week's test is also a means to an end, Gordon added. Not only is it an opportunity for teams to get used to the new spoiler angles and tires, it also establishes a baseline for what to expect during the upcoming season.

What's more, it will allow NASCAR officials an opportunity to judge whether further refinements to spoiler angle or tire tread wear are necessary in the future. Some, like Gordon, wouldn't mind if rear spoilers were completely eliminated at some point.

"This is a good transition for us to step into now, to get some races under our belt, see how it goes and then go from there," Gordon said. "But, it's got to be hand in hand. It can't be just cut the spoiler off. It needs to be tested at the wind tunnel.

"NASCAR can't just be cutting things off the cars; they need to be tested. They need to have wind tunnel numbers so they know exactly what they're doing with these cars, and then they have to work with Goodyear in testing."

Still, Gordon is in favor of the new changes and is eager to see how they play out on the racetrack, both in Las Vegas and during the upcoming season.

Jerry Bonkowski covers NASCAR for ESPN.com. He can be reached at Motorsportwriter@MSN.com.