Defending champion Hideki Matsuyama and Bo Van Pelt both fired 8-under 64s Thursday and share the lead after one round of the Memorial.
Both leaders have one PGA Tour win.
Jason Dufner was tied for the lead heading to the 18th at Muirfield Village Golf Club, but found water off the tee. That led to a closing double-bogey, which dropped him into a tie for third at minus-6. He was joined there by Russell Knox, who bogeyed the ninth, his last.
Ryan Moore and Brendon Todd headline a group of seven players tied for fifth at 5-under 67. They stand alongside Ken Duke, Harris English, Kevin Kisner, David Lingmerth and Kyle Reifers.
Major champions Jordan Spieth, Justin Rose and Keegan Bradley are among nine players tied for 12th at minus-4.
Five-time winner Tiger Woods rebounded from a tough start for a 1-over 73. That left him tied for 85th place.
Woods bogeyed three of his first four holes from the 10th. He had another bogey, a double-bogey and two birdies the rest of his opening nine. Woods played his second nine at minus-3 with three birdies and six pars.
