Put meat lean side down on piece of heavy duty foil, large enough to wrap around meat, in large shallow pan or roaster. Pour liquid smoke over brisket. Seal in foil and marinate overnight in refrigerator.
Pour off most of liquid. Season meat with salt and pepper, and cover with Worcestershire sauce. Place lean side up on foil, wrap, and bake 4 1/2 hours at 300. Remove from oven, unwrap and pour barbecue sauce over meat. Cover again with foil and bake another 1 1/2 hours. Chop and serve on buns, or slice thin and serve with remainder of sauce.
1 1/2 cups catsup
1/4 cup Worcestershire sauce
1/2 cup brown sugar
1 tsp. celery salt
1/2 tsp. Tabasco sauce
Mix all ingredient over low heat, stirring til well blended. Note: Barbecue sauce can be poured on brisket at beginning of cooking period. Beef may then be baked 6 hours without unwrapping.