Beat the cream cheese until light and fluffy.
Add sweetened condensed milk; blend thoroughly.
Add 1/3 cup lemon juice and vanilla, stir until it is thickened.
Slice 3 bananas, line crust with banana slices (dip bananas into 2 tbsp lemon juice to prevent browning.
Cut the fourth banana into thin slices. Dip in remaining lemon juice. Garnish top of pie with banana slices.
Chill 2-4 hours before serving.