AUGUSTA — Bubba Watson won the Masters two years ago with his brand of "Bubba golf," producing shots of raw skill and wild imagination. His strategy now is to keep it simple, and he is halfway to another green jacket.
    Watson took over Augusta National on Friday with 75 minutes of brilliance and power. On another demanding day of crispy greens and swirling wind, he ran off five straight birdies on the back nine and wound up with a 4-under 68 for a three-shot lead over John Senden.
    There's nothing fancy about his golf, except for his outrageous length. He has made only two bogeys in 36 holes. He has missed only eight greens.
    "It's not science here," Watson said. "It's try to hit the greens. And if you're hitting the greens, that means you're obviously hitting your tee shots well. So that's all I'm trying to do is just hit the greens ... maybe throw in a birdie here or there. That's what I've done the last two days and it's worked out so far."
    Watson made bogey on the 18th hole with a shot that bounced left of the green and into the gallery. He finished at 7-under 137, giving him the largest 36-hole lead at the Masters since Chad Campbell in 2006.
    Senden qualified for the Masters a month ago with his win at Innisbrook. After a rugged start, he played the final 14 holes with six birdies and no bogeys for a 68 that puts him in the last group at a major on the weekend.
    Adam Scott also made a late recovery with three birdies on the back nine to salvage a 72, along with his hopes to join Tiger Woods, Nick Faldo and Jack Nicklaus as the only players to win back-to-back at Augusta. Scott was four shots back at 141, along with Thomas Bjorn (68), Jonas Blixt (71) and Jordan Spieth, the 20-year-old from Texas who looked solid on the mystifying greens and shot a 70.
    "Bubba is tearing it up," Spieth said. "So we've got to go get him."
    The chase includes the ageless Fred Couples, who won the Masters a year before Spieth was born. Couples, cool as ever at 54, had another 71 and was five back.
    Woods, who missed the Masters for the first time in 20 years because of back surgery, won't be the only guy watching on television. Phil Mickelson made another triple bogey — three shots from the bunkers on the par-3 12th hole — for a 73 and missed the cut for the first time since 1997. So did Sergio Garcia, Ernie Els, Luke Donald, Webb Simpson, Dustin Johnson and Jason Dufner.
    Rory McIlroy nearly joined them. He hit one tee shot over the fourth green, past the head of Adam Scott on the fifth tee and into the bushes for a double bogey. Another shot hit a sprinkler head and landed in the azaleas behind the 13th green. He had to make a 6-foot par putt to make the cut at 4-over 148.
    Watson seems further away from the field than just three shots.

U.S. Open champion Justin Rose was nine shots behind, but not ready to give up because the leader often comes back to the field — although he admitted that former champs are less likely to collapse.

"But there's no give on this golf course," Rose said. "The hole can start looking awfully small, and those lakes can start to look awfully big."

The only thing that looked big to Watson was the size of the cup.

His birdie streak started and ended with a 9-iron to short range on par 3s — 3 feet on the 12th, 4 feet on the 16th. He got up-and-down for birdies on the par 5s. And in the middle of that great run was a putt that defines the vexing greens of Augusta.

Watson had a 40-foot putt on the 14th hole that probably traveled 50 feet after it turned nearly 90 degrees to the left and rolled into the cup. Just his luck, Garcia had a chip shot that rolled over the spot where Watson had marked his putt and showed him the way.

"Without Sergio's chip, I probably would have three-putted it," Watson said.

That's really the only break he needed in the second round. His golf is amazingly simple for such a complicated personality. Watson, whose victory at Riviera in February was his first since the 2012 Masters, said he was helped by not having all the attention on him this week. He didn't have to host the Champions Dinner. He didn't have to go through the process of returning the green jacket.

Even so, the Masters is just getting started.

The 36-hole leader goes on to win the Masters just over one-third of the time, and only two players — Mike Weir in 2003 and Trevor Immelman in 2008 — have done it since 2000. And while Watson is a major champion, this will be the first time he sleeps on the lead at a major.

"It's starting to get pretty easy to drop shots out there," Scott said. "Tomorrow is a big day for everyone."