The Chase for the NASCAR Sprint Cup, the sanctioning body's 10-race, season-ending playoff round, has officially begun at Chicagoland Speedway, site of Sunday's 400.

Here are five things you need to know about this weekend.

Qualifying rained out -- The bummer was that qualifying was rained out Friday, which meant the grid for Sunday's race will be set by practice speeds from the one-hour and 25-minute session earlier in the day.

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As a result, defending NASCAR Sprint Cup Series champion Kevin Harvick, who was fastest in practice, will start on the pole, followed by Joey Logano, Brad Keselowski, Martin Truex Jr. and Ryan Newman.

Since rain was in the forecast, most of the teams practiced in qualifying trim all day long in anticipation of the rainout.

"I think today is kind of a unique scenario because everyone thought it would rain," said Harvick. "Everybody put a lot of emphasis on qualifying."

"Track position is key," said Logano. "This first round (of the Chase) is all about clicking off good finishes, which is what it is all about. A nice start here will really start that, and we are off to a nice start, starting on the front row."

There are two rounds of Sprint Cup practice scheduled for Saturday at 1:30 p.m. ET and 4:30 p.m. ET. During that time, drivers will try to get a handle on their cars in race trim for Sunday's main event.

How the Chase works -- A quick refresher course on the Chase: The opening round of the Chase is called the Challenger Round and includes 16 drivers. After the third race of the Chase, the top 12 drivers -- winners of the first three races and the remaining drivers highest in points -- will advance to the Contender Round. After three more races, the field will be cut to eight drivers for the Eliminator Round.

And following the completion of the Eliminator Round, four more drivers get tossed, leaving the top four drivers to race heads up for the championship in the season finale at Homestead-Miami Speedway. There are no bonus points in the Chase, and the points are reset after every round, so all drivers who advance start with the same points total in the next round.

In the first round, especially, you'll see a lot of guys points racing -- all they need to do to make it to the next round is finish the Challenger Round 12th or better in points. Others will want to win right away to lock themselves into the next round of the Chase. Once you win, you are guaranteed to advance to the next round, no matter where you finish in the other two races in your round.

"You've got to have one or the other," Kyle Busch said of the debate between winning and being consistent. "If you haven't got consistency, then you better be winning. If you're having consistency, then you don't have to be winning, but there's nothing better than being able to win and move yourself automatically."

Winning isn't everything, yet -- Through the first 11 editions of the Chase, the winner of the first race has only gone on to win the championship that season three times: Kurt Busch in 2004, Tony Stewart in 2011 and Brad Keselowski in 2012.

So it's not hugely important to win on Sunday. But it is essential not to have a bad race.

Last year, the four guys knocked out after the first round of the Chase all struggled at Chicagoland: Kasey Kahne finished 12th, AJ Allmendinger 22nd, Greg Biffle 23rd and Aric Almirola 41st.

Still, expect some drivers to push hard on Sunday. "The situation you always want to be in is to be able to win, especially the first race in every bracket and then Homestead," said Keselowski, the two-time and defending Chicago winner. "If you can take that approach, I think anyone would."

Restarts and pit stops will be key on Sunday -- Most often these days, races are won or lost in two places: on pit road, during the final stop of the race, and during the final restart. There is a lot of confusion among the drivers about NASCAR's policies on when they can accelerate coming to the green flag. There's been lots of finger-pointing between drivers about either jumping restarts or laying back to get a run when the track goes green.

"I believe the restarts are still kind of -- there's still a lot of gray area there that I don't think everyone in the garage understands exactly what is allowable and what's not," said Carl Edwards, one of the championship favorites.

"The restart is neat because it gives you an opportunity to get an advantage," said Edwards. "It is tough and it's a dynamic part of the race. It's just where do you draw the line? Can I go 50 feet early or 100 feet early? If the leader doesn't go, can I just go and beat him into Turn 1? I don't know exactly what's allowable and, yes, you don't want to have the start happen and have no penalty thrown and have given up an advantage. Let me put it simply: If you do the restarts by the book -- the way they say to go at it -- you'll get passed by about four guys every restart, so nobody really knows what to do."

The head games have begun -- Kevin Harvick got the Chase off to a feisty start on Thursday, when he vowed to stomp the Joe Gibbs Racing Toyotas into the ground. This was but the first salvo in what likely will be a lengthy battle of wills and strategies among the serious title contenders.

Recall back to 2010, when Denny Hamlin appeared to have a lock on the championship with two races to go, but Jimmie Johnson began a subtle campaign, talking about how much pressure was going to be on Hamlin in those last races. And, sure enough, Hamlin and his team each made a big mistake in the final two races and Johnson won his fifth consecutive title.

Likewise, Tony Stewart laid some pretty heavy mind games on Carl Edwards in 2011 during his miraculous late-season run to a third championship.

"He's an instigator," said Jeff Gordon of Harvick. "I'm not surprised. I saw a few antics yesterday. The thing is everybody has their own way of going about it. ... It's just Kevin's personality. "

And it's worth noting a basic premise applicable to Harvick at the moment: It ain't braggin' if you can back it up. And Harvick is the defending Sprint Cup champion and was fastest in Friday's practice at Chicagoland Speedway, which earned him the pole for Sunday's race when qualifying got rained out later in the evening.

This is going to be fun to watch over the next 10 weeks.