World number one Rory McIlroy has defended his comments about Tiger Woods and Phil Mickelson being in "the last few holes of their careers".

McIlroy first addressed the issue during his pre-tournament press conference at the Tour Championship in Atlanta, which will not feature either Woods or Mickelson for the first time since 1992.

The 25-year-old was asked if that represented a changing of the guard in golf and said: “Not really. I mean, Phil has played well in parts this year. He came really close to winning the PGA (finishing second behind McIlroy). I feel like he’s gotten a little better as the year has went on.

“But it’s a lot of golf for him to play in such a short space of time. So you could see he was getting a little tired the last couple of weeks. And, I mean, Tiger’s not here just because he’s been injured or he is injured. He hasn’t had the opportunity to play.

“But I think if he gets back and when he gets back to full fitness, you’ll see him back here again. So I’m not sure... they’re just getting older. Phil’s 43 or whatever (actually 44) and Tiger’s nearly 40 (Woods turns 39 in December).

“So they’re getting into the sort of last few holes of their career. And that’s what happens. You get injured. Phil has to deal with an arthritic condition as well. So it obviously just gets harder as you get older. I’ll be able to tell you in 20 years how it feels.”

Despite simply stating the facts, McIlroy’s comments inevitably generated comments on social media and the four-time major winner later wrote on his Twitter account: “Got a question today about Tiger and Phil... Gave an honest answer, was very complimentary about the two best golfers of this generation.

“Golfers on average have a 20-25 year career, both into the back 9 of their careers... Don’t think there’s anything wrong with saying that.”

* Play was suspended in the first round of the KLM Open when Paraguay's Fabrizio Zanotti was hit on the head by a golf ball.

Zanotti, who won the BMW International Open earlier this season, was on the 16th fairway when he was injured by a ball struck from the 14th tee.

The 31-year-old received treatment on the course and was then taken to hospital. Zanotti had started his round from the 10th at Kennemer Golf Club and was level par after six holes when the incident occurred.