Rinse chicken, pat dry. preheat oven to 350 F. Combine the pineapple juice, sugar, lemon juice, and mustard in a small bowl. Mix together and stir in the pineapple. Place chicken breast in 9x13 inch baking dish coated with cooking spray. Spread the pineapple mixture over the chicken. Bake in preheated oven for 45 min or until juices run clear.