MIX mayonnaise and pepper sauce.
GRILL chicken 4 to 5 min. on each side or until done (165ºF). Cut into thin slices.
FOR each serving: Warm 2 pita breads on grill. Spread 1 Tbsp. mayonnaise mixture onto 1 pita; top with 1 cheese slice, about 3 oz. chicken, 1/2 cup lettuce and 1/4 cup tomatoes. Top with additional 1 Tbsp. mayonnaise mixture, second cheese slice and second pita.