Preheat oven to 350º F and lightly grease a square baking dish with butter or non-stick spray.
Place chicken, cheese, celery and bacon in a large bowl.
In a smaller bowl, whisk together mayonnaise, ranch mix, lemon juice, Worcestershire sauce and onion powder, and season with salt and pepper.
Stir mayonnaise mixture into chicken until everything is evenly coated, then transfer everything to greased baking dish.
Top baking dish with crushed potato chips, then place in oven and bake for 25-30 minutes, or until mixture is hot and bubbly and cheese is melted.
Remove from oven and serve hot.
