Rory McIlroy Twitter row at Irish Open in Killarney
Northern Ireland's US Open champion Rory McIlroy has stumbled into a row on Twitter at the Irish Open in Killarney.
The 22-year-old responded to criticism of his first round 70 in Killarney from BBC radio commentator Jay Townsend.
McIlroy replied "your opinion means nothing" to Townsend on the social networking site.
McIlroy's opening round was spoiled by a double bogey on the 18th, ruining his promising start.
All three of Northern Ireland's recent major winners - McIlroy, Darren Clarke and Graeme McDowell - are playing in the competition. As is the Republic's three-time major winner Padraig Harrington.
McIlroy was four under after 10 holes but bogeyed the 11th and then found the water with an iron shot at the 18th.
Townsend, a former European Tour player who now works for BBC radio, 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!"
When asked about the exchange McIlroy said: "Well I stand by my caddie".
The US Open winner has had JP Fitzgerald on his bag since the middle of his first full season as a professional in 2008.
"He's been having a go at JP every now and again since then and this was the first time I've responded - it was the straw that broke the camel's back," said McIlroy.
"Now I've blocked him on Twitter so I won't be reading anything more."
India's Jeev Milkha Singh currently leads the tournament on eight under par.
McDowell lies one over while newly crowned Open champion Clarke finished with a two under round of 69.
'Hard to take'
McIlroy had begun his day brightly with birdies at the fourth, sixth, eighth and 10th holes before falling down the leaderboard.
"I put myself in a good position but my second nine was pretty disappointing," said McIlroy.
"I played some scrappy golf on the way in and a six at the last is hard to take, but I'm still not too far away.
"The course is in great condition and has been set up really nicely.
"The greens are a little slow but at least you can be aggressive with your putts."
McDowell carded two birdies and three bogeys as he struggled to an unconvincing 72.