In a medium bowl, whisk together the olive oil, ranch dressing, Worcestershire sauce, rosemary, salt, lemon juice, white vinegar, pepper, and sugar. Remove from grill, rest for 2-3 minutes and serve.
Place chicken in a gallon size sealable bag. add marinade, seal and gently toss to coat. Refrigerate for at least 8 hours.
Preheat the grill for medium-high heat.
Grill chicken for 5-6 minutes per side, or until the chicken's internal temperature reaches 165° Fahrenheit (75° Celsius).
Remove from grill. Tent with foil and rest for 2-3 minutes. Serve.