A magnificent run of five consecutive birdies on the back nine powered 2012 Masters champion Bubba Watson to a three-stroke lead after Friday's second round of the 78th Masters.
With a dazzling display of precision on one of golf's most intimidating layouts, the 35-year-old US left-hander fired a four-under par 68 to stand on seven-under 137 after 36 holes at Augusta National.
Watson beat Louis Oosthuizen in a playoff for the green jacket to claim his first major crown but had not won again until capturing the title at Riviera two months ago. Now he has made himself the man to beat this weekend.
"I felt really good," Watson said. "It's not science here. It's try to hit the greens and if you're hitting the greens that means you're obviously hitting your tee shots well. That's what I've done the last two days and it's worked out so far."
In Masters history, there has never been a longer birdie streak before the weekend than Watson's run and only five longer ones at any stage in the event.
"You're so focused on what you are doing, you are not really thinking you have just had three in a row, four in a row," Watson said.
"It's one of those things. Everyone has had that stretch before, playing with their buddies or playing in a tournament, so it's not that big a deal when we think about it.
"But at the Masters, it makes it a big deal."
Australian John Senden, who qualified only by winning in March at Tampa, was second on 140 after also shooting 68.
Defending champion Adam Scott, the first Aussie to win a green jacket, joined Denmark's Thomas Bjorn, Sweden's Jonas Blixt and American Jordan Spieth sharing third on 141.
Americans Fred Couples, Jimmy Walker and Jim Furyk shared seventh on 142.
Watson, who began the day one off the lead, birdied the seventh and made bogey at nine before launching his birdie run with a five-footer at the par-3 12th and followed with another from 10 feet at the par-5 13th.
Watson, ranked 12th, curled in a long putt with 15 feet of break over slopes at the 14th, owning a debt to playing partner Sergio Garcia.
"Sergio had a chip and had to go right over my coin, basically, and I watched his ball. He checked it up and then it went straight sideways about 15 feet, and he hit it about eight inches from the hole," Watson said.
"Having that putt from the same line, I knew where to aim it, knew kind of what the speed was. It was a lot different than what I was thinking, and then somehow it just went in.
"Without Sergio's chip, I probably would have three-putted it."
Watson followed with a chip to eight feet to set up a birdie at the par-5 15th and rolled his tee shot, a 9-iron from 176 yards, feet from the cup to set up a birdie at the par-3 16th.
A par at 17 ended the run and a bogey at 18 dropped Watson one stroke closer to the field but his earlier heroics made him the man to catch.
Watson wants to "stay level"
"I've been lucky enough to win here," Watson said. "Just got to keep my head down, same thing I've been doing the last two days, try to stay level, not too energized, not too excited."
Not since Tiger Woods ran off a Masters record-tying seven in a row starting at the seventh hole of the third round on his way to a 2005 title has there been a longer birdie run at Augusta National.
And not since David Toms made six in a row from the 12th in the last round in 1998 has there been such a streak on the back nine at the Masters.
Senden followed his lone bogey at the fourth with six birdies in the last 14 holes to grind into second.
Bjorn opened with two birdies and birdied four of the last five holes to fire a 68.
Scott opened with three bogeys in five holes but battled back with three birdies in four holes starting at the 12th to fire a 72.
Second-ranked Scott could join Jack Nicklaus, Woods and Nick Faldo as back-to-back Masters winners and would overtake injured world number one Woods atop the rankings with a two-way share of third this week.
"Anyone could make a move tomorrow with some great play," Scott said.
Spieth and Blixt were the leaders among 24 Masters newcomers who were trying to become the first rookies to win since Fuzzy Zoeller in 1979.
Only 10 of them made the cut, including Aussie Oliver Gross, the only amateur into the weekend.
Only 51 of 97 starters reached the last two rounds, including expected title contenders Rory McIlroy and Jason Day on the number at four-over 148.
Two reigning major champions missed the cut -- British Open champion Phil Mickelson on 149 and 2013 PGA Championship winner Jason Dufner at 154.
Others finishing over the cut mark were Garcia, one-time Friday leader Marc Leishman of Australia and Ernie Els.