Preheat oven to 350 degrees F.
Combine crumbs, sugar and butter in bowl. Scrape into 9-inch springform pan; press evenly over bottom and 1 inch up sides.
Beat cream cheese and sugar at medium speed in large bowl until blended. Beat in eggs, vanilla and lemon juice until blended. Pour into prepared pan.
Bake in 350 degree oven for 50 minutes or until puffed and golden. Transfer to a wire rack and let stand for 15 minutes. Increase oven temperature to 450 degrees F.
Stir together sour cream, sugar and vanilla in small bowl until blended. Spoon over top of cheesecake, spreading evenly.
Bake 10 minutes or just until the topping is set. Transfer cheesecake to rack to cool completely. Refrigerate overnight. Remove side of pan. Garnish with mandarin oranges, if you wish. Makes 16 servings.