JOLIET, Ill. — Martin Truex went from a completely unraveled tire that left him a lap down to his first stint at the top of the Sprint Cup Chase for the Championship standings.He can thank a late caution in what has been an emotional year for the small-team driver.Truex shot to the front after a late restart and pulled away to give Furniture Row Racing a victory to open NASCAR's playoffs on Sunday at Chicagoland Speedway."I've had a lot of practice at it," Truex said about the on-track obstacles. "I think my approach really changed two years ago when (girlfriend) Sherry got diagnosed with cancer. My approach to all those things changed and made me a better driver."NASCAR announced after the Teenage Mutant Ninja Turtles 400 that Truex's No. 78 Toyota failed the laser inspection, but the infraction was not bad enough to negate the victory. Truex is expected to receive a point penalty this week.Rookie Chase Elliott appeared on his way to an easy win until Michael McDowell blew a tire and spun out to bring a caution with five laps left. Elliott and Truex pitted for tires while Ryan Blaney, Kasey Kahne and Chase contender Carl Edwards stayed on the track.Truex restarted fourth and Elliott fifth, and Truex quickly got to the front and held off Joey Logano on the final lap for his third victory this season. Truex is guaranteed to move on when the Chase field is cut from 16 to 12 in two weeks.Truex, whose team gets technical support from Joe Gibbs Racing, made the last four in the 2015 Chase. His 2016 season started with near miss at the Daytona 500 and a Coca-Cola 600 win, while Sherry Pollex has battled ovarian cancer. She's now in remission."You have to understand, this isn't the end of the world." Truex said of racing setbacks. "We can overcome it. That's what we did today."Elliott, a rookie, finished third, followed by Blaney and Chase driver Brad Keselowski, who sits second in points."It's not yours until it's over," the 20-year-old Elliott said. "That's part of life, man. You're not dumb. We've all watched this stuff long enough to know these races don't go green that long."Truex led early in the race only to have his tire come completely unraveled. It led to an unscheduled stop that left him a lap down in the 400-mile race."The hard compound came off it," Cole Pearn, Truex's crew chief, said. "I guess (Goodyear) saw a couple other tires and came down and told us a certain sequence number had an issue."Jimmie Johnson led 118 laps and was second when he was caught speeding on pit road during the last green-flag stop. He yelled "no way!" on his radio when told he had to serve a pass-through penalty. The six-time series champion finished 12th, but his car also failed laser inspection and he could receive a 10-point penalty this week.