Rory McIlroy: My head-to-head record against Jordan Spieth counts for nothing
Rory McIlroy insisted his head-to-head record against Jordan Spieth would count for nothing when the 97th US PGA Championship got under way at Whistling Straits on Thursday.
The world's top two players have 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.
"Okay, maybe if it was a final round and we were in contention to win you can maybe look into it a bit more, but first two rounds, I wouldn't put too much importance on that."
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.
"Jordan has played phenomenal golf for the last 12 months," McIlroy said. "He's taking up a lot of the limelight this year, deservedly so. I mean it's one of the best years of golf that we have seen in a long, long time.
"I guess as well we live in such a world that everything's so reactionary and everything happens so quickly that a year ago after I won this tournament it was the Rory era, and then Jordan wins the Masters and it's the Jordan era.
"Eras last about six months these days instead of 20 years! But it's just the way the world is."
McIlroy, Spieth and Open champion Zach Johnson were due out at 1320 local time (1920 BST), with Tiger Woods, 2010 winner Martin Kaymer and Keegan Bradley among the early groups.