After a 30th-place qualifying effort Friday, Johnson's No. 48 Hendrick Motorsports Chevrolet was fastest in the first of two practices on the 1.5-mile oval before slipping to fourth in the second and final session.
Series runner-up Carl Edwards was in the opposite situation. Edwards, who trails Johnson by 141 points going into Sunday's Ford 400, qualified fourth, but had a so-so final day of practice. He was seventh in the opening session, but fell to 23rd in the last hour.
That wasn't a good omen for Edwards, who has to lead laps and finish at or near the top to have any hope of catching Johnson, who needs to finish only 36th or better to match Cale Yarborough's 30-year-old record of three straight Cup titles.
"Just the fact that we're starting in front Jimmie, that's a small victory for us," Edwards said after qualifying. "The better chance we can have, the better pit stall selection we can have, the more traffic he's in, all of those things add up to a better chance for us to make this Cinderella story happen and come back from nowhere and win this."
One of the few things that could give Edwards a chance is for Johnson to have a parts failure of get caught up in a crash.
Chad Knaus, Johnson's crew chief, said starting in midpack is not where he would like his driver to be.
"There is a lot of mayhem that goes on back there, especially at this racetrack with the way the groove widens up," Knaus said. "You get people all over the racetrack, so that's always a concern.
"People say, 'Well, that's just bad luck if you get caught up in a wreck when you're at the back of the field.' But, quite honestly, if you hadn't qualified so poorly you wouldn't be back there and you wouldn't be in the wreck. Obviously, engine issues, mechanical issues ... you just don't even know what's going to happen. So I'm worried about everything, to be quite honest with you. But the thing I'm most concerned about, is just making sure we keep (Edwards) in eyesight."
Denny Hamlin, another of the 12 drivers in the Chase for the championship, was fast on Saturday. He was right behind Johnson in the first practice and led the "Happy Hour" session, just ahead of three-time Homestead winner Greg Biffle.
But the spotlight will be on Johnson and Edwards. As 2007 Homestead winner Matt Kenseth can attest, the race winner gets little attention if somebody else wins the championship.
"It's cool to win anytime you can, especially the last race of the year because you can't get beat the next week," Kenseth said. "You've kind of got all winter to be a little bit happy about your win and enjoy it."
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