In a small bowl, whisk together the celery salt, garlic powder, and onion salt. Generously Season both sides of the brisket with the seasonings. Place meat in a foil lined baking pan to fully enclose meat. Pour Worcestershire sauce over the meat.

Crimp the foil tightly over the meat. Return to the refrigerator and marinate overnight.

When ready to cook, bring the meat to room temperature and bake at 275 degrees for 5 hours. Remove foil and pour about 1 c. barbecue sauce over the meat. Bake for an additional 1 hour with the foil open.

Cool and slice into thin pieces.