Woods was three shots behind when he stood on the sixth tee Saturday. Nine holes later, he was five shots ahead and still rolling. The signature shot was a 3-wood from just over 300 yards that stopped 10 feet away for an eagle at No. 9.
Woods was at 16-under 197, seven shots clear of Brandt Snedeker (66) and Marc Leishman (68). Its his largest 54-hole lead on the PGA Tour since he was eight shots in front at the Buick Invitational early last year.
The previous best at Cog Hill was a 63, which Woods shot two years ago in the final round to win. He tied the tournament record set last year at Bellerive by Jim Furyk.
A victory Sunday would give Woods the lead in the FedEx Cup standings.