Rory McIlroy last won a major at the 2014 US PGA ChampionshipRory McIlroy got his bid to end an eight-year major drought off to a solid start as he set the early pace on day one of the US PGA Championship.
After a stutter, Northern Ireland's four-time major champion closed with a birdie to card a five-under 65 and take a one-shot lead into the clubhouse.
He was in a marquee group alongside Americans Tiger Woods and Jordan Spieth at Southern Hills in Oklahoma.
Woods signed for a four-over 74 while Spieth finished with a two-over 72.
"Overall, it was a great day," said McIlroy. "Great to get of to a great start at a major championship for a change.
"I came in here knowing my game is in good shape so it is a matter of executing the shots you know you can - I need to replicate that tomorrow, Saturday and Sunday and not get ahead of myself. It's a great start."
World number 40 Tom Hoge, who won his first PGA Tour event at the AT&T Pebble Beach Pro-Am earlier this year, and fellow American Will Zalatoris are McIlroy's nearest challengers at four under par.
Scotland's Robert MacIntyre, who started on the 10th, posted a level-par 70 that saw two birdies on his front nine cancelled out by a pair of bogeys after the turn, putting him level with England's Tyrrell Hatton.
The world's three top-ranked players - Masters winner Scottie Scheffler, US Open victor Jon Rahm and Open champion Collin Morikawa - are among the late starters with the wind expected to pick up in the afternoon.
McIlroy stutters after fast start
Starting from the 10th tee, McIlroy's putter was as fiery as the sweltering Tulsa heat and his nerve as cold as the staggeringly priced on-site refreshments as he made four successive birdies to wrangle the lead after six holes.
The 33-year-old is looking to record a third PGA Championship win, with the second of his Wanamaker Trophy successes coming in August 2014 at Valhalla, just a few weeks after he had won his first Claret Jug at the Open.
It was McIlroy's fourth major title and the great Jack Nicklaus proclaimed afterwards that the fresh-faced prospect could go on to "win 15 or 20" of golf's elite prizes.
Eight years later and McIlroy is yet to add to that tally - instead he has 14 top-10 finishes and a runner-up place at last month's Masters.
He would couch that by pointing out, as he did to BBC Radio 5 Live's All About: The Open podcast, that he has won pretty much everything else in that time, but his recent major form has been characterised by sluggish starts that have shot him out of contention.
Heading into this event, McIlroy was a cumulative 35 over par in the first rounds of major championships since his last title in 2014, having been 19 under for his opening rounds in the four years before that.
On Thursday - in the absence of defending champion Phil Mickelson, the man McIlroy edged out for his last major victory - he maintained his early charge by nudging in another birdie at the 500-yard par-four second, his 11th, to move two strokes clear of the field and then salvaged par on the next hole.
Showing his daughter Poppy an old picture of himself on the media centre wall earlier this week, McIlroy is reportedly said to have joked to herexternal-link that "that was when daddy was good".
A fifth major title would certainly reinforce that he still is and, despite missing a birdie chance on his 13th, McIlroy clipped out of the greenside bunker on the par-five fifth and rolled in the following putt to extend his advantage to three strokes.
But his momentum was stunted with the first blemish on his card at the par-three sixth moments later, squirrelling a par putt narrowly wide, and a wayward drive followed as McIlroy's stellar opening round threatened to unravel down the stretch.
He scrambled for par before a second bogey of the day allowed Hoge and Zalatoris to take a share of top spot, only to then roll in his seventh birdie from 20 feet on the final hole to sign for his joint second-lowest opening round in a major - only going lower with a 63 at the Open in 2010, when he finished tied third.
Woods appears in pain at finish
Tiger Woods has won the US PGA Championship on four occassionsWoods made a remarkable comeback at Augusta National in April, 14 months after a career-threatening car crash that left him unable to walk for three months.
The world number 818 said that felt like "Everest" and, after more time on the golf course, insisted that he was now ready to contend.
He started brightly with birdies on his first and fifth holes.
But the 15-time major champion appeared to be struggling the deeper into his round he got, wincing after tee shots and he closed with successive bogeys to finish four over.
"Lots of treatment, lots of ice," said Woods about his recovery before Friday's second round.
Spieth, who needs to win this major to complete a career grand slam, had a mixed round in which he carded two birdies and four bogeys.
