Woods fired a 9-under 61 to match his lowest round ever in relation to score, beginning the day birdie-eagle before dropping in six more birdies. He opened the back nine with four straight birdies for his fourth career 61, 13 years after he did it at the storied Firestone Country Club course.
Woods had a chance for a record-tying 59 before missing birdie tries inside 10 feet on the 15th and 17th holes.
Woods is 13-under through 36 holes, a whopping seven strokes ahead of defending champion Keegan Bradley and Chris Wood. Bradley and Wood each fired 68s.