A round of six under par 64 gave Zach Johnson a one-stroke lead after the first round of the Colonial in Texas.
Starting from the 10th hole Johnson opened with a 40-foot birdie putt before saving par at 12 after finding a greenside bunker. Four birdies in a row at Hogan's Alley put Johnson on course for his first win since the same tournament two years ago.
A four-way tie for second place, one stroke back from Johnson, involved Jason Dufner, US PGA Tour rookie Harris English, Tom Gillis and Kyle Reifers.
Johnson said: "I got off to a good start, just hit some quality shots. I didn't put myself ever in a position that was too worrisome.
"I kept the golf course in front me. I attacked when I could attack. I had a couple of nice saves when I needed it. ... I've got zero complaints."
Dufner, winner of last week's Byron Nelson Championship, started the Colonial with three birdies and went to five under after a 10-foot birdie at the eighth but then carded two bogeys in three holes.
Sergio Garcia, the 2001 Colonial champion in the same group as Johnson, shot a 66 to match Chris DiMarco, Tommy Gainey and Andres Romero.
English, a former Walker Cup player, played his first full round at Colonial just days after he qualified for the Open with two fine rounds at Gleneagles.
He said: "Three bogey-free rounds I have had in a row, which I've never done.
"I'm playing solid golf and not really getting out of position. I'm getting my putter going. I'm hitting it to 15 or 20 feet a lot and seemed to be making a good many of those. It's just been good."
Garcia had an eagle three at the 558-yard first hole which moved him to five under through 10 holes.
Garcia, without a win on the PGA tour for four years, had a bogey at three but saved par out of bunkers on his closing two holes.
Defending champion David Toms, in the group with Johnson and Garcia, had only one birdie in an opening 74.
