Grilled Hawaiian Chicken

6 chicken breasts, boneless
2 cups pineapple juice
2 tablespoons Worcestershire sauce
2 ounces soy sauce (regular or low sodium)
2 tablespoons brown sugar

Combine all ingredients except chicken and stir. Poke about 5-8 sets of holes in each chicken breast. Put chicken in marinade, making sure it is covered in the mixture. Add more pineapple juice if necessary. Cover tightly, and refrigerate for 24-36 hours. Grill when desired.