The 2015 Xfinity Series champion from Prosper, Texas, led a race-high 169 of 500 laps, including the final 61, to become the third consecutive non-Playoff competitor to win in the Round of 16.
The 24-year-old Gragson from Las Vegas, Nevada, led the final 25 laps en route to his sixth victory of the 2022 Xfinity Series season at Thunder Valley.
Following an eventful conclusion of the 2022 Xfinity regular-season finale at Thunder Valley, Hemric and Sieg secured the final two vacant spots to the 2022 Xfinity Playoffs.
The 28-year-old Majeski from Seymour, Wisconsin, became the first Truck Series competitor to secure a Championship 4 finale spot by claiming his first career victory at Thunder Valley.
The NASCAR Cup Series and Camping World Truck Series travel to Bristol Motor Speedway this week for some dirt track racing under the lights while the Xfinity Series is off.