Combine whiskey, brown sugar, soy sauce, water, Worcestershire sauce, lemon juice and garlic powder, mix well.
Place roast into a plastic bag; add marinade (saving some back for basting) and seal. Place in a dish; refrigerate overnight, turning occasionally.
Grill over medium coals (with Jack Daniels' Barrel Chips, soaked in water - if you can find them), about 20 to 25 minutes per side for medium. Baste occasionally with extra marinade.
To serve, cut into thin slices.Makes 4 to 6 Source: