Series: NASCAR Sprint Cup. Date: Thursday, qualifying races. Site: Daytona mile tri-oval. Start time: 2:00 p.m. (et). Laps: 60 (each race). Miles: 150. 2011 Winners: Kurt Busch (race 1). Jeff Burton (race 2). Television: SPEED. Radio: Motor Racing Network (MRN)/SIRIUS NASCAR Satellite.

Thursday's Gatorade Duel at Daytona -- the twin 150-mile qualifying races -- will set the starting field for the Daytona 500. With 49 teams entered in "The Great American Race," six of them will not make it into Sunday's big show.

Last weekend in Daytona 500 time trials, Carl Edwards won the pole, while his teammate, Greg Biffle, secured the outside pole to give Roush Fenway Racing and Ford the front starting row. These are the only drivers who have locked down their starting positions in the 500-mile race. Edwards will lead a field of 25 cars to the green flag in the first qualifying race. Biffle will start first in the 24-car field for the second event.

The top 35 in last year's owner points are guaranteed a starting spot in the Daytona 500. Three drivers -- David Stremme, Tony Raines and last year's race winner, Trevor Bayne -- finished outside the top 35 last season, but they are warranted a position in the Daytona 500 based on their qualifying speeds. Terry Labonte, the 1984 and 1996 Cup champion, also is assured a spot if he has to use a champion's provisional.

Therefore, 10 drivers will vie for the four final positions in the Daytona 500.

Michael Waltrip, Michael McDowell, Mike Wallace and Robby Gordon will attempt to make it into the Daytona 500 when they compete in the first qualifying race. Waltrip has competed in the Daytona 500 each year since 1987 (25 consecutive races). He won it in 2001 and '03.

Kenny Wallace, Dave Blaney, Joe Nemechek, Bill Elliott, Robert Richardson Jr. and J.J. Yeley will try to race their way in during the second qualifying event. If Labonte races his way into the Daytona 500 during the qualifiers, then Elliott, the 1988 series champion, is assured a starting spot with at least the champion's provisional.

Elliott has 28 Daytona 500 starts to his credit.

The odd-number starting positions for the Daytona 500 will be based on the finishing order of the first qualifying race, and the even-number starting spots will be determined by the outcome of the final qualifier.