Rickie Fowler birdied the last three holes to take the lead in the PGA Tour's Phoenix Open, overcoming a sluggish start in front of the largest crowd in golf history.
Justin Thomas went the other way, wasting a brilliant opening run with another late meltdown.
Fowler shot a four-under 67 to reach 14 under with a round to play at TPC Scottsdale's Stadium Course, the fan-friendly layout packed with an estimated 216,818 fans.
Saturday's crowd pushed the week total to 654,906, just short of the record of 655,434 set last year.
"I really made some good swings coming in," Fowler said.
"I just wasn't getting the ball close enough and finally on the last few there I was able to get some good looks."
Former Arizona State players Jon Rahm and Chez Reavie were a stroke back along with Bryson DeChambeau.
Phil Mickelson, another former Sun Devils star, was two shots behind as he rode the crowd support.
"It means a lot to me," he said.
"It's very helpful and very important to my success.
Another local resident, Aaron Baddeley, is the leading Australian, seven shots from the lead in a tie for 21st after a 66.
Marc Leishman (five under, 68) and Cameron Smith (three under, 74) are the only other Australians who survived Friday's cut.
World No.4 Thomas, last year's PGA Tour player of the year, birdied the first six holes to take the lead.
But then had to fight to shoot an even-par 71 after a back-nine meltdown.
He dropped six strokes in a three-hole stretch, making a bogey on the par-four 14th, a triple bogey on the par-five 15th and a double bogey on the rowdy par-three 16th.
Fowler, a four-time tour winner, began his birdie run with a 17-footer on 16 and connected from nine feet on the par-4 17th and 18th holes.
He also birdied 13 after playing the first 12 in even par with a birdie and a bogey.
"I just kind of had to fight through it," Fowler said.
"The swing was just a fraction off.
"It wasn't bad, still made some good swings out there, but just had to try and get the ball in the short grass, get some looks and try not to make many mistakes."
