Tiger Woods carded one of his best rounds yesterday at the WGC-Cadillac Championship tournament in Florida, perhaps due to a vigorous workout that morning. Spies saw Woods, who shot 6 under par in the first round of the tourney alongside Rory McIlroy and Luke Donald, arrive at Equinox South Beach for a workout at 8 a.m. According to a source, Woods was “all business” during his session, and was spotted doing stretching, shoulder moves, squats, lower-back extensions, lunges, biceps curls and triceps exercises for more than an hour, along with other early morning gym rats. Actor Kelsey Grammer was one of them — but he stuck to cardio.