Rory McIlroy joked he was now like Beatles drummer Ringo Starr having fallen to number four in the world rankings ahead of this week's Irish Open.

The defending champion and host for this week's event at Portstewart on the rugged Northern Ireland coastline, had dropped to third in the world after missing the cut at the US Open last month.

He then fell a further place behind No.1 Dustin Johnson and second-ranked Hideki Matsuyama when Jordan Spieth won the Travelers Championship to move into third.

"I am back to Ringo," McIlroy said smiling.

"It only bothers me I'm not where I want to be. But I feel like there's been a couple of things that have been out of my control this year that have led to that with the injuries and stuff."

McIlroy had to adjust to new clubs in 2017 after Nike stopped manufacturing equipment, suffered a rib injury which has limited him to just three tournament appearances since the Masters and had the happy distraction of getting married in April.

"Like I've said all along, winning golf tournaments and playing well takes care of the rankings," said McIlroy.

"It's funny, I don't look at it as much now as I would if I was number one. If I was Dustin Johnson, I would be looking at that thing every Monday morning." 

Four-time major winner McIlroy said he was realistic about his form having missed so much of the season, but was still determined to get into contention every time he tees it up.

"The good thing is I know where I am and I realise that I'm a long way off where I want to be, but I can't think about that at the minute," said the 28-year-old.

"I just have to think about trying to win golf tournaments, trying to get in contention again at golf tournaments, first of all.

"And then just playing well, and playing well takes care of a lot of that stuff."

McIlroy played practice rounds in the past week not only at Portstewart and nearby Royal Portrush, which will be the venue for the 2019 British Open, but also Royal Birkdale which hosts the third major of the year in a fortnight's time.

McIlroy has struggled with his putter this year, changing clubs frequently, so it was notable that he was accompanied at Birkdale last week by putting coach Phil Kenyon.

"With Phil's help I have whittled it down to just one putter I want to use," McIlroy said.

"Phil walked around 18 holes with me at Birkdale last Thursday and then I spent a little bit of time with him on the putting green after that. It feels good."