Phil Mickelson used a blazing start to open up a four-shot lead over a pack of three golfers that included Masters champion Hideki Matsuyama midway through his third round at the PGA Championship on Saturday. Mickelson, who began the day with a one-shot share of the lead with South African Louis Oosthuizen, carded four birdies over his first seven holes and reached the turn at the Ocean Course at four-under-par 32 and nine under on the week. That allowed the 50-year-old Mickelson, bidding to become the oldest major winner in history, to separate himself from the pack while Matsuyama, Oosthuizen and South African Branden Grace shared second place. Four-times major champion Brooks Koepka, playing in the penultimate pairing with Grace, bogeyed the par-four ninth and was a further shot adrift. Mickelson, who picked up the most recent of his five major championships at the 2013 British Open, made a sensational start with birdies at the second and third holes, the latter after his approach shot from a waste bunker settled two feet from the cup. He then birdied the par-four sixth where he drained a 17-footer and made another at the par-five seventh after his putt for eagle settled five inches from the hole. Japan"s Matsuyama, bidding to become the first golfer to win multiple majors in the same season since Koepka in 2018, offset an early bogey with a trio of birdies over a five-hole span to stay in contention. Jordan Spieth, seeking a win this week to complete a career Grand Slam of winning golf"s four major championships, was in a four-way share of the clubhouse lead after a three-under par 69 left him at even par for the tournament. "Very pleased with climbing back to even. I hate being over par at a golf course. I mean, it"s like my biggest pet peeve regardless of when it is in the tournament and I just hate seeing an over-par score next to my name," said Spieth. "So it"s nice to be tied with the course with a chance to beat it tomorrow." Defending champion Collin Morikawa (74) was 12 shots back of Mickelson while Northern Irishman Rory McIlroy (74), who won the PGA Championship at Kiawah Island in 2012 and was a favourite to win the year"s second major, was a 14 shots adrift.