Pádraig Harrington insists Rory McIlroy's must roll back the clock and regain the self-belief that brought him four major wins in just four years.

Eight years ago, Harrington predicted McIlroy could give Jack Nicklaus's record of 18 major wins a run, providing he continued to win at a clip of three every four years.

But just days after McIlroy won The Open and then made it four major wins in three years by capturing his second Wanamaker Trophy at Kiawah Island, the Dubliner warned the Holywood star had to win his majors quickly or risk seeing his huge driving advantage eroded by a new generation of millennials.

"Age is on his side but not necessarily time," Harrington said in July 2014. "If he putts okay, he's going to be right there. But with the kids coming out of college now, in five to 10 years' time, there are going to be a lot of players like that.

"At the moment, he has the ability to go into the next number of majors as the favourite for a long number of years. But in time — and Tiger looked invincible for such a long time — the kids in college now are going to learn from Rory and come out with similar games.

"He is young and he's got time to win more majors, but the more he wins, the quicker, the better. There might be three players like him now; in 10 years' time, there might be 15."

Seven years and five months after his fourth major win, McIlroy (32) must now contend with younger players like Jon Rahm and Bryson DeChambeau, not to mention peers Brooks Koepka and Dustin Johnson.

Harrington still believes McIlroy will win more majors, but as he said to Nick Dougherty on Sky Sports in Abu Dhabi on Sunday, the world number eight must regain his bullet-proof self-belief.

"When he was winning, he absolutely stood on the tee and didn't care about anybody else," Harrington said. "He knew if he played his game, he was going to win.

"Obviously, the field has caught up. There are plenty of other big guys out there – big hitters, good drivers of the ball. The depth is stronger now.

"It's not as easy for him to win because there's other good players, but I would suggest, to bring the best out of him, he's just got to be comfortable with who he is and what he's doing.

"I know myself when I was winning my majors, it was just a process of: 'I know I'm going to win them, maybe not this week but I'm going to be there or thereabouts in X amount of majors.

"If I play well in three out of four majors, I'll be in contention in two, and over two years, I should surely win one or four and all of a sudden I win three."

"I was so comfortable that it was my time. Rory was very much like that. You look at his performances back in the day, nobody could stay with him on the golf course.

"Yes, players can stay with him on the golf course now, but he has to believe, he has to get back to that state of, 'I'm doing my thing and if I keep doing it over and over, I might not win this week, but I'm going to win plenty of them'."

McIlroy remains convinced he will win more majors, and he will have a chance to build some confidence for the Masters as he chases his third win in the Slync.io Dubai Desert Classic this week.

The Co Down man did not enjoy last week's windy test in the Abu Dhabi HSBC Championship and a return to the Emirates Golf Club, where he recorded his maiden professional win in 2009 and won again in 2015, is the perfect antidote.

He's joined in Wednesday start at a revamped venue for the $8 million Rolex Series event by Harrington, Shane Lowry and Jonathan Caldwell, as well as Open champion Collin Morikawa and world number five Viktor Hovland.

New world number 47 Séamus Power is skipping this weeks' Farmers Insurance Open at Torrey Pines, where Patrick Reed defends and world number one Rahm seeks his third win at the venue where he captured the US Open last June.