Kurt Busch set the fastest time of the day on Saturday, the Stewart-Haas Racing driver posting a best lap of 26.322s (136.768mph) in the first of the day's two practice sessions on the one-mile, low-banked tri-oval.
Full times from Saturday's practice sessions
Busch, who is returning to race duty this weekend after being suspended from events at Daytona, Atlanta and Las Vegas because of allegations of domestic abuse made by his former partner, was 0.075s faster than Penske's Brad Keselowski in the same session.
In the later practice, Busch's team mate and this weekend's Sprint Cup race pole winner Kevin Harvick was back in charge albeit with a slightly slower time of 26.363s (136.555mph) with Matt Kenseth second on the timesheets for Joe Gibbs Racing, 0.049s off Harvick's pace.
Busch - who will start from eighth place on the grid for Sunday's CampingWorld.com 500 - was still very much on the pace and finished in third place in the later session, with Keselowski also in the top ten in seventh place.
The day did not go quote so well for AJ Allmendinger in the #47 JTG Daugherty Racing entry after an engine issue meant that the team was forced to swap out his Chevrolet power unit between sessions. He will now have to give up his anticipated 22nd place start on Sunday as a result, and consequently have to drop to the back of the grid.
"They saw something they didn't like," Allmendinger. "I didn't like the temperature and that was it. They made the call. I just worry about the race car."
"We didn't qualify as well as we wanted to anyway, so we decided to take the opportunity to change it now and eliminate any doubts," elaborated Allmendinger's crew chief Brian Burns. "We have a good race car and ECR Engines have been awesome all year. We are just taking some precautionary measures to make sure we are good to go to the end."
"What has been awesome about this whole ECR package is this is the first time I've has something like this happen in over a year," Allmendinger added. "The guys are working hard. They will fix it. More importantly we have just got to make the Kingsford Chevy better. We are not very good right now."
Once the engine was swapped out, Allmendinger was still able to get back out in the final practice session of the day and run 26 laps to make sure everything was more to his liking.
See full times from Saturday's practice sessions
Get the latest NASCAR news straight to your Twitter feed! CLICK HERE to follow Crash.net's new dedicated NASCAR Twitter feed