With his Cup-leading seventh win this season, the reigning three-time points champion padded his lead over Mark Martin to 108 points in the next-to-last Series race in 2009.
If Johnson places 25th or better next week at the season-ending Ford 400 at the Homestead-Miami Speedway, he will win the title, regardless of Martin's finish.
"At the start of the race, we were a little loose but still running second or third," said Johnson, who was season-worst 38th at last Sunday's Dickies 500 in Fort Worth, Texas.
Jeff Burton, Denny Hamlin, Martin and pole sitter Martin Truex Jr. completed the Top-5 finishers Sunday.
Jeff Gordon finished ninth, falling 169 points behind the leader, and will be eliminated from title contention when Johnson starts at Homestead.