Ryan Moore birdied five of his first seven holes en route to a 7-under 65 that puts him one ahead of Jordan Spieth after the opening round of the Memorial.
Only two of his seven birdies were longer than 10 feet, and the only time he came close to a bogey was on his opening hole.
Martin Kaymer, Marc Leishman, Vaughn Taylor, Bud Cauley and Anirban Lahiri are at 5 under.
Meanwhile, Tiger Woods made a pair of late birdies to salvage a 70 in his first round since missing the cut at the PGA Championship.