Jordan Spieth fired four birdies in a four-under par 66 on Friday to take a one-shot lead in the Charles Schwab Challenge as Phil Mickelson missed the cut in his first event since his historic PGA Championship triumph.
Spieth, who started the day tied for the lead with Sergio Garcia, was one-under for the day and facing a 23-foot birdie putt at the third when a thunderstorm halted play for more than two hours.
The American rolled in the putt when play resumed, adding an 11-foot birdie at the sixth and a 20-footer at the 14th for an 11-under par total at Colonial Country Club of 129.
"(The) putter still felt pretty good," Spieth said. "I came out of the rain delay and I made a nice putt on three, and really felt like I had a chance to birdie almost every hole on that front nine and even into the back nine.
"But I didn't swing it as well," he said. "I knew I was going to kind of have to manage my way around the golf course a little bit, and fortunately did a really great job of that."
"It's nice if you play a bogey-free round," added Spieth, who got up and down for par from a greenside bunker at the 16th and rolled in a 16-footer from the fringe for par at 18.
He overtook Jason Kokrak, who set an early target with six birdies in a five-under 65 that put him in the clubhouse on 10-under before the rain delay.
Garcia had two birdies and a bogey in his one-under 69 before the delay to head a group on eight-under 132 that also included Colombian Sebastian Munoz and Patton Kizzire, who both shot 65.
Spieth said fatigue might have been a factor in his lack of sharpness late in the round.
He played alongside Mickelson, who had two bogeys in the last three holes in a one-under 69 for a two-over total of 142 - one shot outside the cut line.
Mickelson made history on Sunday at Kiawah Island, winning the PGA Championship for a sixth major title and, at 50, becoming the oldest man to win one of golf's Grand Slam events.
He started the day three-over and opened with a bogey but with three birdies in four holes had battled back to get himself inside the cut line.
He was even for the tournament after a birdie at the 15th, but he was unable to get up and down from a greenside bunker at both 16 and 18 - leaving himself a 10-foot par putt at the last that he couldn't get to drop.
While Spieth thought his back nine left room for improvement, he was looking forward to the weekend on a Colonial course where he won in 2016.
"I'm in a good spot at a familiar place, and just going to have to go check on the weather and set a goal for the weekend," Spieth said.
Leading second-round scores on Friday in the US PGA Tour Charles Schwab Challenge at Colonial Country Club in Fort Worth, Texas (USA unless noted, par-70):
129 - Jordan Spieth 63-66
130 - Jason Kokrak 65-65
132 - Sebastian Munoz (COL) 67-65, Sergio Garcia (ESP) 63-69, Patton Kizzire 67-65
133 - Maverick McNealy 70-63, Charley Hoffman 71-62, Adam Hadwin (CAN) 66-67, Erik Compton 65-68
134 - Kramer Hickok 66-68
135 - Brian Harman 69-66, Robert Streb 67-68, Collin Morikawa 69-66, Kevin Streelman 69-66, Vincent Whaley 69-66
136 - Talor Gooch 67-69, Tony Finau 69-67, Kevin Kisner 69-67, Brandt Snedeker 66-70, Justin Rose (ENG) 68-68, Daniel Berger 68-68, Brendon Todd 72-64, Kyle Stanley 69-67, Cameron Tringale 67-69