Rory McIlroy has hit back after his caddie was criticised by former pro Jay Townsend during the Irish Open.
Townsend, who is now a pundit for the Golf Channel, described McIlroy's course management in Thursday's opening round as "shocking".
He went on to endorse a tweet that claimed the US Open champion should hire Tiger Woods' former caddie Steve Williams, as his current caddie, JP Fitzgerald, was not up to the job.
"It was a comment too far, I've got to stand up for my caddie," said McIlroy.
Townsend then tweeted: "McIlroy's course management was shocking. Some of the worst course management I have ever seen beyond under-10 boys' golf competition."
McIlroy quickly replied: "Shut up... you're a commentator and a failed golfer, your opinion means nothing!"
The 22-year-old said he felt it was necessary to stand up for his caddie as the media generally don't interview caddies after a round.
He also explained that the feud had been ongoing since 2008 when Townsend criticised Fitzgerald after an event in Switzerland.