Johnson won the Tums Fast Relief 500 Sunday at Martinsville Speedway to leap in front of former series frontrunner Brad Keselowski and take the Chase for the Sprint Cup lead into Texas next week.
The day couldn't be considered a disappointment for Keselowski, however. He qualified poorly Friday and started the race 32nd, then battled all day to steadily move through the field to reach sixth, a splendid finish, all things considered.
Following Johnson in the top five in Sunday's race were Kyle Busch, Kasey Kahne, Aric Almirola and Clint Bowyer.
The new Chase standings show Johnson in front, Keselowski second, Bowyer third (26 points behind), Kahne fourth (29 behind) and Denny Hamlin, the day's big loser, 49 behind in fifth.
Hamlin was 20 points behind Keselowski entering the race and was shooting for big gains, but he ran into a roadblock at what has been one of his best tracks.
With 130 laps left in the race and Hamlin running in the top 10, his Toyota lost power. He restored power by switching batteries, but the car's gauges continued to spin wildly, indicating more serious problems. A few laps later, Hamlin's car stalled on the frontstretch, bringing out the day's eighth caution.
Hamlin was pushed to the garage area by a wrecker, putting a dark cloud over his championship chances. He eventually returned to the track 34 laps down but finished 33rd. The problems apparently were caused by a faulty master control switch.
"One of these days it's going to be our time," Hamlin said. "It's just not right now."
Johnson said he doesn't consider Hamlin out of the race for the title and cautioned that the road ahead is a risky one.
"Anything can happen," Johnson said. "We've done a very nice job over these seven (Chase) races to put ourselves in the points lead. We've had a variety of different races finish with fuel mileage and things like that that kept us out of victory lane.
"We're ready to race under any conditions. He (Keselowski) is a great driver, and it's a great team. The next few races will tell the tale. We could wad it up next week, and Clint Bowyer's the champion."
Johnson said Hamlin's problem is proof that gremlins can pop up and stop anyone in the championship race.
"It can happen to me or the 2 (Keselowski)," he said. "With three races left, anything can happen. I know it's frustrating for me to say that. You're looking for somebody to call the shot. But you've got to play the game. You've got to run the race. With three races left, there are a lot of laps to run."
Crew chief Chad Knaus said the 48 team is stepping up, as it typically does in the season's twilight weeks.
"When it's time to go, that's when this team excels and makes things happen," Knaus said. "I think we're able to pull from our past and get out there and do what it is we need to do."
NOTES: The weekend wasn't a total loss for Hamlin. He made a late-race run to victory in Saturday's Kroger 200 Camping World Truck Series race. Hamlin nudged aside leader Matt Crafton with six laps remaining to move into first and claim the win, an aggressive action that irritated Crafton, leading him to bump into Hamlin's truck on the cool-down lap. ... After missing two races because of concussions, Dale Earnhardt Jr. returned to competition in Sunday's race, finishing 21st. He ran in the top 10 much of the day. ... One of the distinctive aspects of Martinsville Speedway, at once the smallest and slowest track in NASCAR, is the set of railroad tracks that roughly parallel the track's backstretch and run behind the small section of backstretch grandstands. Freight trains often rumble along the tracks during races. ... Only three races remain in the battle for the Sprint Cup championship - at Texas Motor Speedway Nov. 4, at Phoenix International Raceway Nov. 11 and at Homestead-Miami Speedway Nov. 18.