Matt Kuchar, the winner of the 2013 Memorial Tournament and co-leader after Friday, shot a two-under 70 in the third round. He is at 14 under, and tied for the lead with William McGirt and Gary Woodland at Muirfield Village Golf Club in Dublin, Ohio.
Kuchar looked to have the outright lead going into Sunday, but a bogey on 18 derailed that hope.
"I've been playing really good golf," said Kuchar. "It was tough for me to swallow being two over early. I was glad to rebound from there. I made three birdies in a row, and had a nice stretch before the delay came."
Jason Day, winner of seven of his last 17 starts, shot a four-under 68, moving to 11 under for the tournament. He is tied for 11th and three shots off the lead, though he was poised to finish at 13 under before a double bogey on 18.
Dustin Johnson, the leader after round one, remains in contention going into the final round. He shot a four-under 68, moving to 13 under for the tournament. He is tied for fourth with Emiliano Grillo, Adam Hadwin and Jon Curran.
Jordan Spieth struggled on Saturday, shooting a two-over 74 to bring his 54-hole score to four under. He is 10 shots off the lead, and tied for 58th.