In a bowl, stir together oil, lemon juice, soy sauce, balsamic vinegar, brown sugar, Worcestershire sauce, garlic, salt, and pepper.
Pierce chicken breasts with a fork all over. Place in a large Ziploc bag. Pour marinade over chicken.
Let marinate for at least 30 minutes. 4 - 5 hours is ideal.
Preheat grill to medium heat. Brush grill with oil to prevent sticking.
Place chicken on the grill. Cook for approximately 5 - 6 minutes per side, depending on the thickness of chicken. The internal temperature of the chicken should reach 165 degrees.
Remove chicken from grill and let rest for 5 minutes.