Place the 4 boneless skinless chicken breasts in a large sealable freezer or zip-top bag and gently pound them with a meat mallet until they are an even thickness.
In a mixing bowl, whisk together 1/2 cup Chick-fil-A sauce, 1/2 cup olive oil, 2 tsp Worcestershire sauce, 1 tsp white vinegar, 1 tsp lemon juice, 1 tsp onion powder, 1 tsp garlic powder, and salt and pepper to taste until smooth.
Pour the marinade into the bag with the chicken, seal tightly, remove excess air, and gently massage the bag so the chicken is fully coated.
Refrigerate the sealed bag for 4 to 24 hours to marinate.
When ready to cook, remove the chicken from the marinade and discard the used marinade.
Grill or cook the chicken (using a cast iron grill pan or outdoor grill) until the internal temperature reaches 165°F (74°C), using grilling tongs to handle the pieces and a meat thermometer to check doneness.
