Tiger Woods had one of the rounds of the day going, reaching 5 under with a hole out for eagle from 95 yards on the par-5 11th hole.
The 42-year-old Armour shot a 68 and a 70 to finish the day at 6-under.
Among those three off the lead were Hideki Matsuyama (71), who earned his first PGA Tour title at the Memorial three years ago, and Jason Day, a former world No. 1 who is a member at Muirfield Village and has never come close to winning.
"Well, I just need to hit better putts".
He was at 14-under 202, and even DeChambeau couldn't help but look back at 2 short birdies that got away.
At the 184-yard par-3 12th, Byeong Hun An hit a tee shot 162 yards at the green, setting himself up for the 6-foot putt for birdie. On a soft course yielding low scores, he made seven birdies to join Stanley (66) at 11-under 133. "If I just keep building on this, with how I'm hitting it right now, I'm in good shape for two weeks from now".
"I recall in the '86 Masters I hadn't won for a couple of years and I got to the last round, and I got into the back nine after struggling on the front nine but then I made a putt on nine and I finally remembered how to play".
DeChambeau wasn't even sure where he was when he finished because so many players worked their way up and down the leaderboard over the final two hours.More news: Atlantic hurricane season starts with forecast of frequent storms
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The three-time Muirfield Village champion had three-putted his opening hole but soon made amends with four birdies from his third to ninth holes and move to three-under par. He had two eagles on Saturday including a hole in one on the par three eighth hole. He hit the ball so pure last Friday that he missed five putts inside 7 feet and still shot 67. It was the first time he has had a share of the lead after any round in his 40th start on the PGA Tour. Justin Rose dropped two shots over the last three holes for a 69 and was four back.
In his front-nine 31, Woods had an eagle and three birdies. Just got to make the adjustments.
That didn't last. Woods ran his 45-foot birdie putt about 7 feet by on the par-3 16th and missed it coming back, and then closed by missing a 3-foot par putt.
"Consequently I missed a bunch of putts", he told ESPN after his round. This week I didn't really have, didn't feel comfortable with my lines and my feel was a little bit off. I played beautifully, actually. That's just human nature but when you have a guy as good as Tiger is and as competitive as he is, he'll break through that barrier and I would not be surprised to see Tiger win this week.
He won the Memorial for the fifth time in 2012, finished 20 shots behind the following year and then injuries took over.
He had played the Memorial only once before, though the 24-year-old Californian has been a regular in central Ohio.
The trio were tied on seven-under par 65 in the Jack Nicklaus-hosted event at Muirfield Village. Woods pulled that so far left the ball went over the creek and into shin-high grass. "But it's nice to have played well enough to make the cut, be able to play the weekend, keep working on my game and hopefully get sharper and sharper".