A brutal crash went down in the closing moments of NASCAR's Geico 500 at Talladega on Sunday ... taking out several cars in the final lap and paving the way for Tyler Reddick to come away with the win.
The dramatic moment took place right before the checkered flag was waved ... when Michael McDowell -- who led 36 laps of the race -- triggered the chaos after attempting to block Brad Keselowski.
The two traded places multiple times, but McDowell's last effort made contact with Keselowski .