In a mixing bowl, whisk together 3/4 cup hot sauce, 3/4 cup sweet chili sauce, 2 minced garlic cloves, and 1½ tablespoons Worcestershire sauce until smooth.
Place 4 boneless skinless chicken breasts in a gallon zip-top bag and, if desired, lightly pound each to an even thickness using a meat mallet or rolling pin.
Pour the marinade over the chicken in the bag, seal, and massage gently to coat all pieces. Refrigerate for a few hours or up to overnight.
When ready to cook, remove chicken from the marinade and discard the used marinade.
Preheat your grill (or a cast iron grill pan) to medium-high heat. Grill the chicken for about 12–15 minutes total, flipping once, until an instant-read thermometer registers 165°F (74°C).
Transfer the cooked chicken to a plate and let rest briefly before serving.