Combine chili powder, cumin, coriander, sugar, salt, cayenne and olive oil in a bowl. Mixture will be a little dry.
Pound chicken breasts with a meat mallet or other heavy object until a uniform 1/4-inch thickness. Use your hands to rub chicken with chili mixture. Place chicken on grill and cook, turning 9 to 10 minutes until juices run clear when the thickest part of the breast is pierced with the tip of a knife. Slice crosswise into strips.