Monster Energy/Pro Circuit/Kawasaki rookie Seth Hammaker became the team's third rider forced to the sidelines in advance of the Thunder Valley National, the second round of the 2021 Lucas Oil Pro Motocross Championship. The Pennsylvania native finished 16th in his series debut at the opening round, which included some laps as one of the early frontrunners in the first 250 Class moto.

Hammaker made the announcement via his personal Instagram, stating that his health will keep him off the starting gate for Thunder Valley but that he's hopeful for a return in time for the High Point National on June 19. Mitch Payton's five-rider lineup is now just down to two competitors, Austin Forkner and Jo Shimoda.