The Northern Irish golfer will lead Europe's charge at the event at New York's Bethpage Black in September and doubts that Keegan Bradley can combine both roles for the US amid speculation that he could turn out in a playing capacity.

McIlroy said: "I've been asked to do that and I've turned it down. The idea of me being a playing captain sometime soon has come up and I've shot it down straight away.

"I don't think you can do it."

There has not been a playing captain at the Ryder Cup since Arnold Palmer did so for the USA in 1963 and McIlroy thinks the expansion of the event means it "would be a very difficult position to be in".

The five-time major champion said: "There's a lot of things that people don't see that the captain does the week of the Ryder Cup, especially now that the Ryder Cup has become so big.

"The captain isn't going to be on the course all day, so the captain is only going to be able to play one session on Friday, one session on Saturday. Would you not rather have the flexibility to go twice if he's playing well? There's just a lot of different things that go into it.

"That's why, and it's just my opinion, I think it would be very difficult to do."

McIlroy returns to action at the BMW Championship this week and has defended his decision to skip the FedEx St Jude Championship last week given his busy schedule for the rest of the year.

The world number two said: "I feel like I'm in sort of a different position to some of the guys. I'm playing nine times between now and the end of the year so I've still got a pretty busy stretch coming up.

"I think that extra week off will do me good with the events coming up - some big events that are important to me. Irish Open, [the BMW PGA Championship at] Wentworth, obviously the Ryder Cup, and I want to try and win my seventh Race to Dubai.

"There's some things that are still important to me that I want to go and play in. That was a big part of the reason why I took the week off last week."