Chastain, who finished runner-up to winner Chase Briscoe in the spring race at Phoenix, led the way in Friday’s 50-minute session with an average lap speed of 133.239 mph.
The first-year driver for Trackhouse Racing earned his first two series victories this season and is looking for his first series title in Sunday’s race.
“I have complete confidence that the speed in our car will be there. Qualifying will be a big emphasis for us, with how cool it is, the way these cars are racing this year, “Chastain said earlier this week.
“One constant all year is that the Trackhouse cars can pass aside from Martinsville where we qualified better than we ever have on short tracks (and) I don’t think I actually passed anybody all day until I started bulldozing them out of the way at the end of the race.
“No thoughts other than going fast.”
Ryan Blaney ended up second-fastest (133.037 mph) and Kyle Busch, who will make his final start for Joe Gibbs Racing on Sunday, was third (132.963 mph).
Tyler Reddick and Kevin Harvick rounded out the top-five.
The three remaining drivers also competing for the series title – Joey Logano, Chase Elliott and Christopher Bell – ended up seventh, 10th and 20th.
Among those drivers who ran at least 10 consecutive laps, Blaney had the fastest average speed (132.272 mph), followed by Reddick, Harvick and Elliott, who was top among the Championship 4.
Elliott also led his title rivals in the 15 consecutive lap averages, followed by Logano and then Chastain.
There were no on-track incidents during the session.
