Cut breasts in half; wipe well with damp paper towels. In large bowl combine sour cream, lemon juice, Worcestershire sauce, celery salt, paprika, garlic, salt and pepper. Add chicken to sour cream mixture, coating each piece well. Let stand, covered, in refrigerator overnight. Next day, preheat oven to 350 degrees. Remove chicken from sour cream mixture and roll in crumbs, coating evenly. Arrange in single layer in large shallow baking pan. Melt butter and shortening together in small saucepan. Spoon half of this over chicken. Bake chicken uncovered 45 minutes. Spoon rest of butter-shortening mixture over chicken. Bake 15 minutes longer or until chicken is tender and nicely browned.