The two-time ARCA Menards Series East champion from Eden Prairie, Minnesota, led 80 of 250 laps and became the 183rd competitor to win in the O'Reilly Auto Parts Series division by winning for the first time ever at The Rock.
The 21-year-old Day from Clovis, California, clocked in a single pole-winning lap at 148.963 mph in 22.717 seconds to become the 217th competitor to win an O'Reilly Auto Parts Series pole position.
The reigning two-time Cup Series champion from Elk Grove, California, went from seventh to first during a 47-lap dash that enabled him to achieve his first NASCAR victory of the 2026 season in Sin City.
Larson who fended off a young racer in the making and Hendrick Motorsports developmental Corey Day in the waning laps of the 25-lap feature by 0.096 seconds.