Mickelson had 11 one-putts and converted all six sand saves in a 2-under 68 in the second round Friday to take the lead at 7-under 133. The world's No. 2-ranked player led Matt Kuchar (64), Brian Gay (65) and Johnson Wagner (71) by one stroke.
"It was probably the best putting round I've had all year," said Mickelson, who needed only 25 putts.
That's because Mickelson kept setting himself up with the short clubs. From the fairways, the rough and the bunkers.
Only four of his one-putts were 9 feet or longer (the longest was 18 feet). Three of those came at Nos. 3-5, the trio of holes known as Colonial's "horrible horseshoe" because of the difficulty and layout of that stretch, where he hit his approach into greenside bunkers each time and saved par. That was part of his final nine holes.
"Those putts kept the round going," Mickelson said. "When I got through those holes, I thought I could get a couple of birdies coming in. I had a couple of good chances."
Mickelson didn't lower his score after that, missing a 6-foot birdie on No. 7 before his short approach at No. 9 bounced over the hole and he slid an 8-footer just past. But the 2000 Colonial champion, here for the first time in three years, still stayed alone at the top of the leaderboard.
Wagner, the first-round leader by two strokes, got a birdie on his second hole, the 611-yard 11th. But he needed three shots from 27 feet for bogey at the par-3 13th and had double bogey after hitting his approach at No. 15 into a water canal. There were no more miscues, but only one more birdie.
Gay had a bogey-free round, including a 46-foot blast out of the bunker at the 171-yard 13th that was the first of his three birdies over the last six holes.
Kuchar, whose only victory on the PGA Tour came in 2002, started his round with four straight birdies. He opened with a 25-foot putt before a pair of 31-footers.
"Seeing a putt go in on the first hole gets you off on the right foot," said Kuchar, who had 26 putts and only one bogey. "It's awfully fun to see the ball fall in the hole."
To make room for an extra wedge, Mickelson hasn't carried a 3-wood at tree-lined Hogan's Alley, the old-style 7,054-yard layout that is pretty much the same as it was when Ben Hogan won there five times from 1946-59.
"This is a tournament where I'll hit a lot of drives, a lot more drivers than I thought I was going to hit in an effort to get it down there and make some birdies," Mickelson said. "I've used every wedge in my bag each round. I think the decision is paying off because I've given myself more birdie opportunities."
Mickelson started with two bogeys his first seven holes, flubbing a short chip shot the 448-yard 14th before missing the green and two-putting from 22 feet at the par-3 16th. Three consecutive birdies preceded the "horseshoe."
