MIX all ingredients except chicken until blended. Pour half over chicken in shallow dish; turn to evenly coat both sides of each breast. Refrigerate 1 hour to marinate.
HEAT grill to medium heat. Remove chicken from marinade; discard marinade.
GRILL chicken 6 min. on each side. Brush with half of the remaining barbecue sauce mixture; grill 2 min. or until chicken is done (165ºF), turning and brushing with remaining barbecue sauce mixture after 1 min.