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.

South Africa’s Rory Sabbatini had no such worries after teeing off in the first group at 0645, the 39-year-old making the most of the calm conditions with birdies on the first, second and fourth.

A bogey on the fifth dropped Sabbatini back into a seven-way tie for the lead with the likes of Hideki Matsuyama and Matt Kuchar, with Sergio Garcia, Thomas Bjorn and Stephen Gallacher all one under.

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.

“We played together at the Players (Championship) for the first two days and he struggled,” said McIlroy, who has recovered from a ruptured ankle ligament in time to defend his title. “We’re all going to have bad days and it just so happened that Jordan had a couple of off days whenever we were playing together.

“But I really don’t think you can look too much into the head-to-head when guys are playing together, especially in the first two rounds.”

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 Tiger 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.

Sabbatini dropped another shot on the sixth to fall back to one under, two shots off the lead now held by Paul Casey, Matsuyama, Robert Streb and Ryan Moore.

Casey had taken advantage of the scoring opportunities on the back nine with birdies on the 10th, 11th and 12th, but 14-time major winner Tiger Woods was level par for the same stretch, missing good chances on 10 and 12 and three-putting the 11th for par from just off the green.

.@TigerWoods tees off on his first round of the @PGAChampionship. #SapphireOnLocation http://t.co/TQjD4Ku6SA

— PGA Amateur Golf (@PGAAmateurGolf) August 13, 2015

Playing partners Keegan Bradley and Martin Kaymer were two and one under respectively, Kaymer returning to the scene of his first major title in 2010.

Dustin Johnson, who missed the play-off between Kaymer and Bubba Watson after being penalised two shots for grounding his club in a bunker on the 72nd hole, was also two under after birdies on the 10th and 11th.

Matsuyama birdied the daunting 18th to reach the turn in 32 and was quickly joined on four under by Johnson, who holed from 30 feet for an eagle on the 16th.

However, their lead was short-lived as Denmark’s Thomas Bjorn covered the front nine in 33 and carded birdies on the 11th and 12th to move to five under par.

England’s James Morrison, who is making his debut in the event, and Spain’s Sergio Garcia were both three under after 11, with Scotland’s Marc Warren on the same score after just six holes.

Woods had three-putted the 14th and had to hole from eight feet to avoid doing the same on the next, but then holed from two feet for birdie on the 16th to get back to level par.