Rory McIlroy will not defend his British Open title at St Andrews after announcing on 8 July he did not want to risk further damage to the ankle ligaments he ruptured while playing football.

The world number one's presence at the spiritual home of golf had looked very doubtful after he suffered the injury during a kickabout with friends and posted a picture of himself wearing a protective plastic boot. His withdrawal was duly confirmed on his Instagram account.

"After much consideration I have decided not to play in the Open Championship at St. Andrews," the Northern Irishman wrote.

"I'm taking a long-term view of this injury and, although rehab is progressing well, I want to come back to tournament play when I feel 100% healthy and 100% competitive."

McIlroy's potential showdown with double major winner Jordan Spieth was expected to be the highlight of the Open but the American will now start the tournament as the favourite.

"Everybody has to have a life too. I played basketball against Michael (Greller, his caddy) a few weeks ago one on one. I do things everyday where you could get hurt. Sometimes there are accidents that happen," said Spieth.

Spieth also revealed a near miss on a fishing trip after he won the US Open last month when a shark took a tuna he was trying to reel in and almost pulled him overboard.

"I don't change much in my life other then a couple of things you're obviously a little more cautious of. But I don't think there is anything wrong with it. Sometime there are fluke accidents. As far as with Rory, we want him back. Everybody does. It's unlucky, it's unfortunate and I'm sure he's taking it harder on himself then anybody else. But I don't think he did anything wrong; it was just an unfortunate situation and hopefully he rebounds very quickly and gets back right to where he was," he said.

The 21-year-old Spieth is ranked just behind McIlroy at number two in the world.