Tony Stewart made sure there was no repeat of Saturday's last corner defeat in the Shootout, and duly claimed victory in the first of Thursday afternoon's Gatorade Duels, the 60-lap heats that determine the starting grid for this weekend's Daytona 500 NASCAR Sprint Cup season opener.

He was helped by the race coming to a slightly premature end when there was a heavy crash just after the white flag had come out. The crash started when Aric Almirola reacted to Jamie McMurray getting slightly unstable: Almirola struggled to hold the car and knocked into Danica Patrick's #10 car running underneath and slightly behind him. Patrick's car was sent shooting through the infield apron and into a high speed head long crash with the inside wall that totally wrecked the car.

Patrick herself was unhurt and walked away from the wreck, although she did appear understandably stunned by the force of the impact. "You just kind of brace yourself and in these situations be glad that I'm a small driver and that I've got room and just kind of hug it in and let her rip," she told reporters after being checked out and cleared by the medical centre.

As Patrick was already pre-qualified for the race due to owners points acquired in a deal with Tommy Baldwin Racing, the biggest blow for Patrick was that her car is a write-off and she'll have to take to a back-up on Sunday. "I'm really just bummed out that we didn't finish the last two corners," she told reporters afterwards.

Her crew chief Greg Zipadelli conceded that "It just sucks ... It puts us behind," but there was no question in Zipadelli's mind that Patrick had been completely blameless for the accident.

"She did what she was supposed to do," he said. "She wasn't doing anything wrong riding around the bottom ... I never saw her car move. But I saw a lot of grown men who couldn't keep their car under control. So maybe they need to work on that."

Patrick's accident had been the third of that opening Duel, with the first coming on lap 9 when Michael McDowell got into the back of David Gilliland and spun the #38 into the outside wall, also involving Juan Montoya and Paul Menard in the wreck. McDowell was able to continue and ended up finishing in sixth place, securing himself a place on the Daytona 500 starting grid alongside Robby Gordon, his fellow qualifier from the first Duel; but Gilliland, Montoya and Menard will all have to take to their back-up cars for Sunday's race, and like Patrick will now be sent to the back of the field for the green flag.

The second accident of the day involved two-time former Daytona 500 winner Michael Waltrip, who spun on the transition from apron to banked race track coming out from a late splash and dash on lap 52. His wreck put him out of the Daytona 500, and also meant that the race did not end as expected as a fuel conservation affair but instead allowed everyone to pit for gas who needed to, while Tony Stewart stayed out and made the most of it at the restart. The late caution also closed up the pack so that some of those cars that had stayed toward the back - like Dale Earnhardt Jr. and Carl Edwards - now had an opportunity to make a bid for the front.

Up to then, Denny Hamlin had led much of the race along with Marcos Ambrose, but their gamble of staying out of the pits at the first caution on lap nine cost them dear later on, and while Ambrose managed to work his way back up to third place by the time Patrick wrecked, Hamlin was not so fortunate and ended up a lap down.

After all the excitement of the first Duel, the second was a much quieter affair and featured a sum total of zero cautions. Polesitter Greg Biffle was never far from the front, although a pairing of Matt Kenseth and Jimmie Johnson pushed to the lead early on and Biffle also had to contend with a feisty Kyle Busch, but midway through the race Biffle claimed the lead and was able to keep it through a round of pit stops.

Unfortunately for Biffle, who had lost touch with anyone able to give him a push assist, Kenseth and Johnson re-teamed for the last three laps of the race and blasted their way back to the front. Kenseth finally slid underneath Biffle to deny his team mate the victory, despite every defence that Biffle could throw up against it.

"We had a lot of speed in our car," said Kenseth. "When we got out front early I could tell that we had a really fast car ... When I saw him on the outside at the end, I decided that was my best shot for the win."

Biffle's attempts to fend him off were ineffective: "We were going so much faster that we were going to go by him regardless," was Kenseth's opinion of the crucial pass. "The problem was, I was going too fast. Even if I wanted to slow down ... I couldn't have. Jimmie was pushing me so hard and we were locked together. I had no other choice. Wherever [Biffle] went, I was going to go the opposite way."

At least for team owner Jack Roush it was a case of keeping the victory in the family, And remarkably for Roush, it was his first Duel win all his time as a team owner: "Painfully it has been brought to my attention that this is the first duel twin 150's we have won in my 25 years," he conceded at the press conference later. "I am certainly embarrassed about that!"

The second Duel handed Daytona 500 starting grid spots for Dave Blaney and Joe Nemechek; JJ Yeley was an early retirement with engine problems, while David Reutimann did a start-and-park for BK Racing and Tony Raines also finished early with a vibration problem, but he was already locked on based on his speed in last weekend's qualifying session. Kurt Busch was hit by a pit lane speeding penalty on lap 42 and finished in 14th position.

The Duels finalise the starting grid for the Daytona 500 race on Sunday afternoon. Carl Edwards and Greg Biffle start on the front row as decided by last weekend's qualifying session, with the two Duel winners Tony Stewart and Matt Kenseth starting immediately behind them, and the Duel runners-up Dale Earnhardt Jr. and Regan Smith on row three.

All the teams will be wary about water temperatures for Sunday's race, with overheating a cause for concern for many even over the mere 60 laps of the Duel events.

Full Duel race results available.

Daytona 500 starting line-up

1. #99 Carl Edwards Ford
2. #16 Greg Biffle Ford
3. #14 Tony Stewart Chevrolet
4. #17 Matt Kenseth Ford
5. #88 Dale Earnhardt Jr. Chevrolet
6. #78 Regan Smith Chevrolet
7. #9 Marcos Ambrose Ford
8. #48 Jimmie Johnson Chevrolet
9. #31 Jeff Burton Chevrolet
10. #33 Elliott Sadler Chevrolet
11. #98 Michael McDowell Ford
12. #20 Joey Logano Toyota
13. #29 Kevin Harvick Chevrolet
14. #18 Kyle Busch Toyota
15. #22 A.J. Allmendinger Dodge
16. #24 Jeff Gordon Chevrolet
17. #7 Robby Gordon Dodge
18. #39 Ryan Newman Chevrolet
19. #1 Jamie McMurray Chevrolet
20. #5 Kasey Kahne Chevrolet
21. #6 Ricky Stenhouse Jr. Ford
22. #55 Mark Martin Toyota
23. #2 Brad Keselowski Dodge
24. #36 Dave Blaney Chevrolet
25. #34 David Ragan Ford
26. #56 Martin Truex Jr. Toyota
27. #43 Aric Almirola Ford
28. #51 Kurt Busch Chevrolet
29. #10 Danica Patrick Chevrolet
30. #15 Clint Bowyer Toyota
31. #11 Denny Hamlin Toyota
32. #47 Bobby Labonte Toyota
33. #38 David Gilliland Ford
34. #87 Joe Nemechek Toyota
35. #42 Juan Montoya Chevrolet
36. #13 Casey Mears Ford
37. #27 Paul Menard Chevrolet
38. #93 David Reutimann Toyota
39. #83 Landon Cassill Toyota
40. #21 Trevor Bayne Ford
41. #26 Tony Raines Ford
42. #30 David Stremme Toyota
43. #32 Terry Labonte Ford