Setting the lineup for the Daytona 500 is a complicated process using three rounds of time trials, two qualifying races and NASCAR's system of provisional starters to determine the starting grid.

* First-round qualifying establishes the front-row starters, whose spots are guaranteed. Second- and third-round sessions are open to drivers who believe they can improve their qualifying times, although under NASCAR rules, if they make a new run, their previous effort is erased, even if their second run turns out to be a slower one.

* Rows 2-15 are filled in by the top 14 finishers (not counting the front-row starters) in the Gatorade 125 qualifying races. The starting lineups for the 125s are based on cumulative time-trial results, with the drivers qualifying first, third, fifth, seventh, etc., lining up for the first 125 and the drivers qualifying second, fourth, sixth, eighth, etc., in the second race. The top finishers in one 125 take the inside positions on rows 2-15, while the top finishers in the other take the outside positions.

* Rows 16-19 are filled based on qualifying times of the drivers who don't earn a spot in the first 15 rows. * Rows 20 and 21 are reserved for regular provisional starting spots, and a 43rd starting position is available to any former Winston Cup champion who does not otherwise earn a starting spot. If more than one driver is eligible for the former champion's provisional, the spot goes to one who is the most recent winner of the championship.

* Any driver who must resort to a backup car rather than the car in which he qualified, including the front-row starters, must go to the back of the field prior to the drop of the green flag. However, for statistical purposes, the position earned in qualifying remains that driver's official starting spot.