Bubba Watson moved one shot ahead of the field after firing his second consecutive three-under par 69 in the third round of the PGA Tour's Memorial tournament on Saturday.
The left-handed American and reigning Masters champion ended 54 holes at 12-under-par 204 at the Muirfield Village Golf Club.
"I have a shot," said Watson. "I'd like the same score tomorrow and let the boys beat me if they can."
In the last eight years, Watson hasn't finished better than tied for 23rd at this $6.2 million event.
American Scott Langley shot a five-under 67 to move into second place. Japan's Hideki Matsuyama posted a three-under 69 and moved into third at 10-under 206.
World number one Adam Scott of Australia carded a four-under 68 and climbed to nine-under, where he is alone in fourth.
Another American lefty, Phil Mickelson, fired a 72 and is tied for 47th amid reports he is among the subjects of a federal probe regarding insider trading.
Mickelson vehemently denied any wrongdoing when he spoke to reporters after his round.
Sunday's final pairing will be an all-lefty affair with Langley and Watson, who also won this year at the Northern Trust Open in Los Angeles.
Watson made birdie on five of his first seven holes Saturday. Sandwiched in there was also a bogey on the par-3 fourth hole. He had a birdie and two bogeys on the back nine.
Langley's bogey-free round included four birdies on the back nine and five in total. He has gone 40 holes in a row without a bogey.
"Any time you shoot in the 60s here, pretty happy about it," Langley said. "Tough place."
Scott is still lurking after shooting his second round of the week in the 60s to sit just three back of Watson.
Scott eagled the par-five 15th and rolled in three birdies. His only blemish was a bogey at the last.
Scott is coming off a victory at the Colonial tournament last week, his first tournament playing as the world number one.
"It's going to be tough," Scott said. "He's (Watson) playing great this year, and I just have to post a number.
"I'm in a good position where I can possibly post a number, and that makes life a little harder for the leader."
Charl Schwartzel of South Africa and American Jordan Spieth both shot 67 and were joined in fifth place on 208 by Americans Billy Horschel (68), Robert Streb (69), Brendon Todd (69) as well as second-round leader Paul Casey of England, who shot 76.