Excitement returned to Anaheim as the 2017 Supercross season started on Saturday and Ken Roczen led the 450 class wire-to-wire and finished ahead of two-time defending Champion Ryan Dungey by 16 seconds. Marvin Musquin took third. Shane McElrath got his first career win in the 250 class and was followed by Aaron Plessinger and Martin Davalos. Check out all the action from A1. Photos by Ryne Swanberg.