Thomas Bjorn surprisingly set the early clubhouse target in the 97th US PGA Championship on Thursday, as Dustin Johnson looked on course to make the headlines once more.
Bjorn has not managed a single top-10 finish this season and was 69th out of 77 in last week's Bridgestone Invitational, but carded five birdies and two bogeys in an opening three-under-par 69.
Johnson was six under par with four holes to play as he looked to make amends for the heartbreak of five years ago and claim an overdue first major title, with playing partner Jason Day and Harris English five under.
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The last time the US PGA was held at Whistling Straits in 2010, Johnson was one shot ahead with one to play and thought his bogey on the 18th meant he would be heading into a play-off with Martin Kaymer and Bubba Watson.
However, the 31-year-old was then penalised two strokes after it was ruled he had grounded his club in a fairway bunker before hitting his second shot, even though spectators had been trampling all over the hazard.
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Johnson had also squandered a three-shot lead in the final round of the US Open two months earlier and he three-putted the 72nd hole at Chambers Bay this year to finish a shot behind Jordan Spieth.
The world number eight, who led after the first and second rounds of the Open before fading badly at St Andrews, started on the back nine and made birdies on the 10th and 11th before holing from 30 feet for an eagle on the 16th.
Further birdies on the first and second were followed by a bogey on the third, where playing partner Rickie Fowler took four shots to escape a bunker and took seven, but Johnson bounced straight back with a birdie on the fourth.
In contrast, former world number one Tiger Woods - who missed consecutive cuts in majors for the first time in his career in the US Open and Open - was three over par after 13 holes.
Defending champion McIlroy and world number two Spieth had been paired together for the opening two rounds, along with Open champion Zach Johnson.
The star trio were not out until 1320 local time (1920BST) and were forecast to face the toughest conditions, with winds gusting up to 28mph expected to make life difficult for the later starters.
McIlroy and Spieth have previously been in the same group four times in their careers, with McIlroy shooting the lowest score five times and Spieth just twice.
However, McIlroy acknowledged all but one of those tournaments took place before Spieth's phenomenal performances in 2015, which have seen the 22-year-old win the Masters and US Open and finish a shot outside a play-off in the Open at St Andrews.
Spieth's victories at Augusta National and Chambers Bay had knocked McIlroy out of the limelight even before the latter's injury setback, but Spieth has missed the cut in both of his US PGA appearances to date, while McIlroy is a collective 34 under par since 2009, 17 shots better than anyone else in that period.
Since the US PGA became a stroke play event in 1958, only Woods in 1999-2000 and 2006-07 has won back-to-back titles. McIlroy is seeking to emulate Woods and also claim a third win in four years following victories at Kiawah Island in 2012 and Valhalla last year.