DUBLIN, June 1, 2014 (AFP) - 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.
Leading scores after Saturday's third round of the $6.2 million US PGA Tour's Memorial tournament (USA unless noted, par-72):
204 - Bubba Watson 66-69-69
205 - Scott Langley 72-66-67
206 - Hideki Matsuyama (JPN) 70-67-69
207 - Adam Scott (AUS) 69-70-68
208 - Paul Casey (ENG) 66-66-76, Charl Schwartzel (RSA) 72-69-67, Billy Horschel 71-69-68, Brendon Todd 71-68-69, Jordan Spieth 69-72-67, Robert Streb 72-67-69
209 - Ben Curtis 69-71-69, Andrew Svoboda 72-69-68, Ben Martin 72-72-65
210 - Bo Van Pelt 72-72-66, Ryan Moore 68-70-72, Rory McIlroy (NIR) 63-78-69, Scott Brown 70-69-71, Chris Kirk 66-70-74, Luke Guthrie 75-69-66
211 - Justin Leonard 68-75-68, Steve Stricker 71-70-70, Ernie Els (RSA) 70-72-69, Jason Dufner 71-69-71, Kevin Na 72-69-70, Kevin Stadler 72-71-68, Hunter Mahan 68-70-73, Brendon de Jonge (ZIM) 73-69-69, Justin Hicks 73-67-71, Camilo Villegas (COL) 71-68-72, Jason Day (AUS) 72-69-70