Phoenix International Raceway's one-mile oval is one of the most puzzling race tracks Nextel Cup teams are tasked with solving. This year, there's another piece to the puzzle: Day-into-night racing.
With lights installed at this uniquely configured race track, the many who have struggled with its precision turns and its divergent ends will now also have to account for a drastic temperature change during the race. The race starts at 8:30 p.m. ET, which is a sun-lit 5:30 p.m. for the drivers. The race will end with the lights on the track and the Sun having gone to bed, though.
"Phoenix is normally a pretty tough track for us," points leader Jimmie Johnson said. "It's flat and fast and you have to really work traffic. Now throw in the fact that we will be running in sunlight and at nighttime and you have made it even more challenging.
"The surface changes because of the temperature changes. That changes the way the car handles. As a driver I have to always be thinking about not only what will make our car good now, but what will make it good Saturday night at 6 p.m."
The key, then, will probably be figuring out the tire setup. With cooling temperatures, the track won't be as slick and the gripping all over the track will change.
"It will be interesting to see how the transition from day to night goes this year," Dale Jarrett said. "We don't have as much information on tires like we did in the past so that could be of some concern as we prepare for that this weekend. But it will be a great show. I've said this before but everything seems to intensify under the lights and I'm sure this weekend will be no different."
As if Phoenix hasn't provided enough intensity over the years.
While PIR is characterized as an oval, that shouldn't suggest any measure of symmetry. After taking the green flag on a straight-as-an-arrow frontstretch, drivers head into Turns 1 and 2, banked at just 11 degrees. Turn 2 shallows before reaching a point, as if the track is striving to form a tri-oval but can't quite make it, and then the remainder of the backstretch points slightly downward, banked at 9 degrees. That's the same banking in Turns 3 and 4, which is why many call this a flat track.
But words like one-mile oval and flat track are misnomers, say drivers, when talking about PIR.
"It's very unique with its configuration, and requires a lot of discipline as a driver," said Dale Earnhardt Jr., who won back-to-back events there in 2003 and 2004. "There are so many opportunities to pass there it's real easy to lose focus and overdrive the corners. It's a mile long but it drives like a short track, and we've always been good on short tracks.
"Turn 4 is everything there. If you butcher (Turn) 4, it ruins your whole lap and part of your next lap."
Drivers who are able to get a good run off of Turn 4 are in good shape. Then they head down slightly more banking in the frontstretch and next two turns, which requires drivers to change their approach from one end of the track to the other.
"It's set up a little different on each end," Mark Martin said.
"Everybody calls it a flat track," Tony Stewart said, "but to me one end is flat and one end has banking to it."
Still, Martin doesn't see much problem navigating opposing corners when you're mindset is right.
"Ultimately," he said, "the key is getting through the corners faster than everyone else."
Tony Stewart has done that better than any other Nextel Cup driver, holding the record for the fastest run at the track when he won in 1999 averaging 118 mph.
Stewart first raced at Phoenix in 1993, driving a Silver Crown car, so he's intimately familiar with the beast.
"With every different division of car that I've run there, I've ended up running a different line," he said. "With that, I've learned a lot about that race track and where the sweet spots are on that race track. ... You learn about all the bumps and where all the bumps are on the race track. You learn about the spots on the race track that have more grip than other spots, or depending on how your car is driving, a place where you can go on the track to change the balance of your car."
Will those change, for him or for others, now that the Series is racing at night?
"I think everyone who has gotten to this level has had plenty of experience in racing under the lights," he said. "No one in this series just started running Nextel Cup cars. We all started at some short track somewhere running races at night, so I think all of us have plenty of experience running under the lights."
Rupen Fofaria is a regular contributor to ESPN.com. He can be reached at firstname.lastname@example.org.