Sprinkle brisket with salt, pepper, and garlic. Place half each of onion rings and celery in bottom of a lightly greased roasting pan. Place brisket over vegetables, fat side up. Top with remaining onion rings and celery. Pour chili sauce and 1/4 cup water over top.
Bake at 300º for 1 1/2 hours, basting every 30 minutes. Pour beer over brisket. Tightly cover pan with double-layered heavy-duty aluminum foil, and bake 3 to 4 more hours.