Rory McIlroy certainly meant it when he said that becoming a major winner in golf would mean his life would never be the same again.

But few people expected so much to change so quickly after the young Ulsterman won the US Open at a canter in June.

Within a month he announced he had split with long-term girlfriend Holly Sweeney and then embarked on a new relationship with world number one tennis star Caroline Wozniacki.

Shortly after that, he said he would be rejoining the US tour next year and making Florida his base.

And now comes the shock news that 22-year-old Rory has parted company with Chubby Chandler, who has been his manager since he first turned professional back in 2007.

The Holywood superstar is switching to the Dublin-based Horizon management group, who already handle the affairs of his great friend, compatriot and fellow US Open winner Graeme McDowell.

‘G-Mac’ was also a client of Chandler’s ISM company, which still retains 2011 Open winner Darren Clarke.

An ISM spokesman insisted last night: “There has not been any fall-out; it’s amicable.”

And in a statement, Chandler said: “We have had a brilliant year. Rory has grown and he leaves us as a major champion.”

McIlroy himself added: “Chubby and his team have played a very important role in my success to date. I have made great progress under them and for that I will always be grateful.”

With McIlroy’s earnings expected to increase more than tenfold thanks to his victory at Congressional, Chandler has now lost his most lucrative client ever.