In slow cooker, place potatoes, carrots and garlic. Rub beef roast with rosemary, salt and pepper; place on top of vegetables. Add water and wine. Cover and cook on LOW 10 to 11 hours or until beef and vegetables are tender.
Remove pot roast; trim fat if necessary. Arrange pot roast and vegetables on serving platter. Cover and keep warm. Just before serving, carve port roast across the grain into thin slices.
For gravy, strain cooking liquid; skim off fat. In small saucepan, combine 2 cups cooking liquid and cornstarch mixture until blended. Cook and stir 1 minute or until thickened.
Garnish beef and vegetables with parsley; serve with gravy.