Matt Kenseth claimed the early advantage in the NASCAR Sprint Cup Chase by winning a delayed Chicagoland race.
Heavy rain showers meant an event originally due to commence at midday local time finally finished at 11pm.
The start was delayed nearly two hours as efforts to dry the track took place, and then further rain forced a red flag stoppage of over five hours on lap 109 of 267.
Kenseth had usurped Jimmie Johnson atop the championship just as the points were reset at Richmond last week.
He and Joe Gibbs team-mate Kyle Busch made their way to the front during the 'daytime' segment of the Chicagoland race and led the majority of laps when it eventually resumed under the lights.
Busch was ahead at the final restart 20 laps from the end, and had a shot at sweeping the weekend following Truck and Nationwide wins.
But Kenseth got the better run at the green and took the lead, then established enough of a cushion to keep Busch at bay to the flag.
Richard Childress Racing's Kevin Harvick fended off Kurt Busch and Jimmie Johnson for third.
Both Harvick's pursuers had to fight back from pit delays. Busch was infuriated by a speeding penalty, while Johnson was erroneously held by an official suspecting a lugnut issue at his second stop and then later had a jack issue.
His team-mate Jeff Gordon came back from a puncture for sixth, followed by Brad Keselowski, Ricky Stenhouse Jr, Clint Bowyer and Ryan Newman.
Polesitter Joey Logano led early on but was one of several drivers to suffer an engine failure, a fate shared by fellow Chase contender Dale Earnhardt Jr and a very disgruntled Denny Hamlin.
Results - 267 laps: Pos Driver Team/Car Time/Gap 1. Matt Kenseth Joe Gibbs Toyota 3h10m56.000s 2. Kyle Busch Joe Gibbs Toyota +0.749s 3. Kevin Harvick Childress Chevrolet +3.626s 4. Kurt Busch Furniture Row Chevrolet +3.808s 5. Jimmie Johnson Hendrick Chevrolet +4.704s 6. Jeff Gordon Hendrick Chevrolet +4.871s 7. Brad Keselowski Penske Ford +5.065s 8. Ricky Stenhouse Jr Roush Fenway Ford +6.856s 9. Clint Bowyer Waltrip Toyota +8.254s 10. Ryan Newman Stewart-Haas Chevrolet +8.712s 11. Carl Edwards Roush Fenway Ford +10.966s 12. Kasey Kahne Hendrick Chevrolet +12.236s 13. Aric Almirola Petty Ford +12.713s 14. Jeff Burton Childress Chevrolet +13.348s 15. Marcos Ambrose Petty Ford +14.700s 16. Greg Biffle Roush Fenway Ford +15.533s 17. Mark Martin Stewart-Haas Chevrolet +15.814s 18. Martin Truex Jr Waltrip Toyota +16.713s 19. Jamie McMurray Earnhardt Ganassi Chevolet +17.638s 20. Danica Patrick Stewart-Haas Chevrolet +18.499s 21. AJ Allmendinger JTG Daugherty Toyota +19.386s 22. Paul Menard Childress Chevrolet +20.085s 23. Dave Blaney Baldwin Chevrolet +23.877s 24. Travis Kvapil BK Toyota +1 lap 25. JJ Yeley Baldwin Chevrolet +1 lap 26. David Ragan Front Row Ford +1 lap 27. Justin Allgaier Phoenix Chevrolet +1 lap 28. David Gilliland Front Row Ford +1 lap 29. Landon Cassill Hilman Chevrolet +1 lap 30. Casey Mears Germain Ford +1 lap 31. Joe Nemechek NEMCO Toyota +1 lap 32. Juan Pablo Montoya Earnhardt Ganassi Chevolet +6 laps Retirements: Denny Hamlin Joe Gibbs Toyota 247 laps Timmy Hill FAS Lane Ford 225 laps Dale Earnhardt Jr Hendrick Chevrolet 224 laps David Reutimann BK Toyota 195 laps Joey Logano Penske Ford 175 laps Brian Vickers Waltrip Toyota 161 laps Cole Whitt Swan Toyota 151 laps Tony Raines Circle Sport Chevrolet 87 laps Josh Wise Front Row Ford 84 laps Reed Sorenson Leavine Ford 68 laps Michael McDowell Parsons Ford 29 laps