Tomac started in 13th place, about 10 seconds off the leaders and in the second half of the field. Cooper Webb, who won the holeshot, went to the lead, with Marvin Musquin close behind. Blake Baggett, Aaron Plessinger and Ken Roczen joined the leaders.
By the end of the fifth lap, Tomac moved into 10th place, and nearing the midpoint of the race, he made the kind of charge that fans have come to expect.
In Laps 10 through 12, he passed Dean Wilson, Chad Reed, and Tyler Bowers to land in seventh place. But with time running out and the leaders running far ahead, his charge ended in the 19th lap when he passed Justin Brayton for sixth.
Meanwhile, Webb held off Musquin, then Baggett to complete a post-to-post victory in the 26-lap race. Baggett finished second, and Musquin, Ken Roczen and Aaron Plessinger rounded out the Top 5.
Earlier Saturday, Tomac was the fastest in both qualifying rounds. Musquin, Wilson, Webb and Tomac teammate Joey Savatgy rounded out the Top 5.
Tomac’s day at Mercedes-Benz Stadium later turned south when he finished eighth in the second of the two heats after losing a duel with Reed for fourth place. While attempting to pass Reed, Tomac made an outside move in the sixth lap, and Reed shut him down. Tomac crashed in the sand and dropped to eighth place.
Cole Seely won the trial and was followed by Wilson, Brayton, Savatgy and Plessinger. Reed finished sixth.
Baggett won the first trial. Webb, Musquin, Bowers and Justin Hill rounded out the Top 5.
At the start of Saturday night’s main event, only 13 points separated the top four riders – Webb, Roczen, Musquin and Tomac – but after Atlanta, the spread widened to 22 points as Webb solidified his lead. Roczen remained in second with 186 points, Musquin was third with 182, and Tomac of Cortez was fourth with 177 points.
Tomac and the Monster Energy AMA Supercross series next go to Daytona Beach for the 10th of 17 races on March 9.