But with a determined charge through the field and a couple of opportune cautions in the final 35 laps, Keselowski regained lost track position and put himself in position to make a dramatic race-winning move after a restart on Lap 250.
 
With third-place finisher Kyle Larson battling Kevin Harvick for the lead on Lap 252, Keselowski powered between the two cars off Turn 2 and grabbed the lead.
 
"I just saw a hole, and I went for it," Keselowski said.
 
He held the top spot for a restart on Lap 262, after an accident involving the cars of Danica Patrick and Ricky Stenhouse Jr., and pulled away to win his fifth race of the year and the 15th of his career by 1.759 seconds over Jeff Gordon, who passed Larson for the second spot in the closing laps.
 
Joey Logano ran fourth and Harvick fifth, as Chase drivers took eight of the top 10 finishing positions.
 
With his second victory at Chicagoland, Keselowski ensured he would advance to the next round of the Chase under a new format that features a trio of three-race elimination rounds and a final race at Homestead to settle the championship between the last four eligible drivers.
 
With the starting order set according to speeds in opening Sprint Cup practice because of a qualifying rainout, Keselowski started 25th and worked his way to the front, only to fall back again when he brought the No. 2 Team Penske Ford to pit road to have the loose wheel tightened.
 
"I’m not really sure what to say," said Keselowski, who can race for the next two weeks without fear of falling out of the Chase. "I don’t really know what happened. I just know we got to the lead. There was traffic and I was just digging and in the zone. The recorder was turned off, so I don’t remember what happened.
 
"I had my head down doing all I could do. We had a great Miller Lite Ford Fusion that I knew from the start would be good, but, man, it was really awesome the last few runs. We really dialed it in and the 2 crew did an excellent job. What a day! Man, I am still pumped!"
 
Larson, driving a backup car after a brush with the outside wall in Saturday morning practice, appeared headed for the first victory of his Cup career, before Carl Edwards‘ cut tire brought out the fourth caution on Lap 231. That yellow, which interrupted a cycle of green-flag pit stops, leap-frogged Keselowski to the fourth spot for a restart on Lap 238.
 
Seven laps later, caution for Clint Bowyer’s contact with the Turn 1 wall set up Keselowski’s opportunity to make the winning move.
 
"Man, I was so close," a rueful Larson said of his lost opportunity. "I didn’t need that caution there. I was just cruising out front, and then we got that yellow, and I had to battle Harvick really hard then. That allowed Brad to get by both of us. It really ended our shot at a win there. We had one more shot there at the last restart, but just didn’t have enough for Brad.
 
"He was really good around the bottom. He was about the only car that I thought could get around the bottom all race long. I had a lot of fun gripping the wall. I ran inches off of it the whole race and finally got into it there battling Jeff. Man, for a back-up car, that was amazing… I just hate it that we came up short."
 
If Larson had speed, Chase drivers Edwards, AJ Allmendinger and Greg Biffle did not. None of the three drivers was quick enough to stay on the lead lap, and with respective finishes of 20th, 22nd and 23rd, all are in jeopardy of elimination after the third race of the Chase at Dover.
 
The real casualty of Sunday’s race, however, was Aric Almirola, who was running sixth just before the engine in his No. 43 Richard Petty Motorsports Ford failed as he was coming to pit road for a green-flag stop on Lap 231.
 
Almirola finished 41st and is in grave danger of missing the cut two races hence.

Up next for the Sprint Cup Series is the Sylvania 300 at New Hampshire Motor Speedway next Sunday (2 p.m. ET on ESPN). It is the second of three races in the Challenger Round of the Chase for the NASCAR Sprint Cup.

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