SHEBOYGAN, Wis. — With six straight 3s on his card, Jason Day looked determined as ever Saturday to finally get his first major win. He shot 6-under 66 and built a two-shot lead at 15-under 201 in the PGA Championship, the third straight major in which he has had at least a share of the lead going into the final round.He is the first player since Phil Mickelson in 2005-06 to lead after 54 holes in three straight majors."One more day left," Day said before heading off to the practice range before the sun set on a wild day along Lake Michigan. "I got to keep pushing forward, keep grinding, keep doing the best I can out there and see how it goes (today)."One shot back was Jordan Spieth, who was five shots behind with two holes to play when he capped off a stunning charge along the back nine at Whistling Straits. He finished with three straight birdies for 7-under 65. "Very pleased to have a chance to win another major," said Spieth, the Masters and U.S. Open winner this year.He is trying to join Tiger Woods (2000) and Ben Hogan (1953) as the only players to win three majors in one year.Branden Grace, tied for the lead with three holes to play in the U.S. Open this year when he hit a tee shot out of bounds onto the train tracks at Chambers Bay, holed a bunker shot for birdie on the 18th for 64, the day's best score, and he was three shots behind, along with Justin Rose (68).Also still in the mix was Martin Kaymer after his 65 left him four shots behind and with plenty of good vibes about his playoff win in the PGA Championship at Whistling Straits five years ago. Saturday featured abundant sunshine and endless action, starting in the dead calm of the morning when Matt Jones finished the storm-delayed second round with two birdies for a two-shot lead. In the hunt at a major for the first time, Jones kept his cool in Round 3 even when his drive landed in a hospitality tent left of the ninth fairway and he chose to play off the blue carpet, over the white fence and just off the green. But he imploded at the end, dropping four shots over the last four holes for 73, which left him 10 under.Day looked like he was headed that direction. One moment it looked as though he was pulling away. The next minute he was pulling himself together. He played a six-hole stretch around the turn in 6 under, which included a 15-foot eagle at No. 11 for his first lead of the round. When he stuffed another approach close on the 14th hole for birdie, he was 16 under. One swing changed everything. He tugged a 5-iron into a bunker left of the 15th green and was surprised by the amount of sand. The first shot didn't make it up the slope and rolled back into the sand, and Day wound up with a double bogey about the time Spieth shifted into another gear. Spieth was trying to stay close enough to have a chance today. The volunteers were slow to post Day's double bogey on the large leaderboard on the 18th green, which Spieth couldn't help but notice as he lined up his 7-foot putt. "I saw Jason was at 16 under, and I said, 'You've got to be kidding me. When is he going to slow down?' " Spieth said. "I did all I could do to finish off the round."