Spieth, Day just as good - McIlroy
World golf's top three are all "pretty close", according to number one Rory McIlroy.
World number one Rory McIlroy believes he is evenly matched with Jordan Spieth and Jason Day.
The Northern Irishman has three wins to his name this year, but has been unable to add to his four majors.
It has allowed Spieth, the Masters and U.S. Open champion and US PGA Championship winner Day to take centre stage.
McIlroy said the trio were capable of pushing each other for years to come.
"In terms of titles and majors won I'm a little bit ahead of them, but in terms of where their games are at the minute and mine - I feel we're all pretty close," he said.
"I feel like the level I played at last year, they saw that and they've attained that - it's always trying to set that bar a little bit higher each and every year.
"I think that's probably what we'll see over the next few years, if guys push one another, the levels will just get higher."
McIlroy said records like Day's 20-under total, a record in a major, at Whistling Straits would be broken.
But the 26-year-old remains confident and said that, when at their best, the trio were unstoppable.
"When they play their best, Jordan, probably his best performance of the year was at the Masters and no-one could catch him," McIlroy said.
"Jason this year, the last couple of weeks even, even more than that, winning in Canada and then winning the PGA, and then last week [at The Barclays]. When he's playing his best it's very hard to live with him.
"And I feel the same way whenever I play my best. I've had a couple of big wins in majors and another couple of wins even this year - winning Charlotte by seven.
"Whenever you play your best and everything sort of clicks together, I don't feel like there's anyone that can beat me."
Day and Spieth are grouped together for the Deutsche Bank Championship starting Friday, with McIlroy also in action at TPC Boston.