Half of the field, including Tiger Woods and Bubba Watson, returned to Whistling Straits early Saturday to finish their second 18.
Woods was even par through six holes Friday, 1 under for the tournament. The overnight cut line stood at 1 over par.
Thick fog delayed the start of play the first two days of the PGA, pushing back tee times and denying the completion of rounds at their scheduled times.
Matt Kuchar holds the clubhouse lead after finishing a 3-under 69 Friday. He stands at 8 under, one shot clear of Nick Watney (68).