Tony Stewart races in front of Jeff Gordon during the LifeLock.com 400 at Chicagoland Speedway. (Jonathan Daniel/Getty Images Photo) » More Photos

Stewart and most of the rest of the leaders pitted under green on Lap 105, and when the stops cycled through on Lap 109, the order was Biffle, Vickers, Stewart, Gordon, Edwards, Truex, Harvick, Kenseth, Johnson and Martin.

Caution No. 3 flew on Lap 113 for Michael Waltrip’s spin on the frontstretch. Most of the leaders pitted under the yellow, but Kenseth, Kyle Busch, David Ragan and AJ Allmendinger stayed out to take over the top four spots, followed by Stewart, Vickers, Edwards, Harvick, Martin and Kahne.

The green flew on Lap 117, with Busch pressuring Kenseth hard for the lead. Stewart, who had two fresh tires, made it a three-way fight as Busch took the lead on Lap 122 and pulled his teammate into second with him, dropping Kenseth Ford to third. But Kenseth had to pit on Lap 125 with a flat right-rear tire, which dropped him off the lead lap.

At the halfway point, it was the two Joe Gibbs Racing Toyotas out front, Busch leading teammate Stewart by 2.383 seconds. Ragan’s Roush Fenway Racing Ford was third, 4.448 seconds of the lead, followed by the Red Bull Toyotas of Allmendinger and Vickers. The second five consisted of Edwards, Harvick, Martin, Johnson and Biffle.

Caution No. 4 came out on Lap 143 for debris. Busch led off pit road, ahead of Stewart, Harvick, Edwards and Vickers as most off the leaders took four tires this time. Busch got a great restart when the track went green at Lap 148, as Stewart and the rest of the leaders got hung up behind the lapped car of Jamie McMurray.

With 167 laps complete and 100 to go, Busch led teammate Stewart by 1.057 seconds, as Stewart was mounting a charge for the lead. Third was Harvick, followed by Edwards, Ragan and Vickers.

Just as Stewart caught leader Busch, a yellow flag flew for debris on Lap 177. An errant spring rubber at the entrance of pit road was the reason for the yellow. Most of the lead-lap cars pitted on Lap 178, with Busch holding the lead over Stewart, Edwards, Harvick, Ragan, Vickers, Johnson, Gordon, Allmendinger and Martin. Kenseth got the Lucky Dog on this stop, which moved him back on the lead lap in 30th place.

The green came out on Lap 183, with Busch again making an excellent restart and using the lapped car of Travis Kvapil as a pick between himself and Stewart. On Lap 192, Edwards passed Stewart for second but was 1.532 seconds behind Busch.

At the 200-lap mark, Busch and Edwards were running nearly identical lap times, the No. 18 Toyota leading the No. 99 Ford by 0.675 seconds. Behind them were Harvick, Stewart, Johnson, Ragan, Vickers, Gordon, Allmendinger and Elliott Sadler.

And then it happened. On Lap 203, Edwards took over the lead from Busch, who to that point had led 125 laps in what had been yet another dominating performance. As has been the case so often this year, once in clean air, the leader was able to open a wide margin. Just six laps after he took the lead, Edwards stretched the gap out front to 1.592 seconds.