Former U.S. Open champion Graeme McDowell has given a strong hint that his Ryder Cup fourballs partnership with world number one Rory McIlroy is a thing of the past.

There has been much media speculation suggesting the two Northern Irish friends are not as close as they were, mainly because of the court case surrounding McIlroy's split from the Horizon management camp the pair once shared.

McDowell said that, if anything, there was more warmth between them now and any break-up on the course will be simply down to the fact they have evolved as individual players since the duo first formed their Ryder Cup partnership four years ago.

"There is no doubt our personal issues have been well documented over the last couple of years," the 2010 U.S. Open champion told a news conference on Tuesday.

"I believe we've both come out of the other end of that probably better friends than we were going into it. Our personal issues are not a problem, that's a fact.

"I think tactically Rory and I's golf dynamic has changed significantly from the first time we ever played together," said the 35-year-old McDowell.

"The older brother to younger brother leadership role I had with him, that's changed. He's the world's number one player, he's a four-time major champion, the dynamic between him and I is changed forever."

Europe captain Paul McGinley sent his players out to practice in four groups of three on Tuesday, with McDowell accompanying French rookie Victor Dubuisson and world number five Henrik Stenson of Sweden.

While suggesting a fourballs pairing with the 25-year-old McIlroy was unlikely against the United States later this week, McDowell stressed that a Northern Irish double act was still on the cards in the foursomes.

"Rory would now be the leader of the two of us," he added. "Perhaps I'm the kind of guy that needs that leadership role a little bit, who needs to feel he is at least on a level with the guy he's playing with.

"I found the better-ball format very difficult with him at Medinah a couple of years ago because he likes to go first, I let him at it, and I kind of come second.

"He is standing there beating it 350 yards down the middle and I put my tee in the ground thinking there's not really a lot of point in hitting this tee shot," said world number 18 McDowell.

"It kind of didn't help my game much at Medinah. Foursomes I think it's different, I think we could still play foursomes really well together."

(Editing by Martyn Herman)