World number one Rory McIlroy has revealed that he has ruptured ligaments in his left ankle playing football.
McIlroy announced the news via Twitter, with an accompanying photograph on Instagram showing himself on crutches and wearing a protective boot.
The news comes less than a fortnight after McIlroy was due to defend his Open Championship title, although the Northern Irishman has perhaps optimistically not yet ruled himself out of the event at St Andrews.
McIlory's showdown with double major winner Jordan Spieth was expected to be the highlight of the Open, which takes place at St Andrews on July 16-19.
Recovery from injuries such as the one reported by McIlroy can take weeks or, in the worst cases, months and even require surgery. McIlroy has, as yet, given no details on the anticipated timescale for his recovery.
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Jack Nicklaus believes it is time for the "young guys to take over" after Jordan Spieth's record-breaking Masters victory on Sunday.
"That was an incredible performance," six-time Masters champion Nicklaus said in a statement. "It was so apparent that he learned down the stretch last year, but you have to remember he was only 20 at the time.
"Now he's a grizzled veteran at 21 years old - just 21. Jordan is so beyond his years. I like everything about the young man. He's polite. He's humble. He handles himself so well, on and off the golf course. And he's obviously a wonderful player and now a Masters champion. I think Jordan Spieth is a great person - just as I think Rory McIlroy is - to carry the mantle for the game of golf.
"I am someone who likes the new generations. I always have. I think it energises the game of golf. We had Arnold's (Palmer) generation, then it came to my generation, then Tom Watson came along and right on down the line to Tiger and Rory.
"And now we have Jordan Spieth. There are some older players who have been terrific for a long time, but actually this might be time for the young guys to take over."
Spieth tweeted about his Masters win earlier:
Well.. I'm glad that wasn't a dream
Tiger Woods injured his right hand in his final round on Sunday at The Masters and after said a 'bone kind of popped out'.
Woods appeared to hit a hidden tree root when playing his second shot out of the pine straw on the ninth.
"A bone kind of popped out and a joint went out of place but I put it back in," Woods said.
"It hurt. It definitely hurt. I didn't know there was a tree root there. I drove my hand or drove the club straight into it. It didn't move. But my body kept moving.
"There was a little joint that popped out and I was able to somehow put it back in, which didn't feel very good, but at least it got back in and I could move my hand again."
Jordan Spieth set out to defy the odds and move a step closer to a first major title as the 79th Masters resumed at Augusta National on Friday.
Spieth held a three-shot lead overnight after carding a superb opening 64 which was just one shot outside the course record and the lowest score recorded in men's major championship history.
The last player to hold the outright lead after the first round and go on to win was Ben Crenshaw in 1984, although Trevor Immelman was joint leader on his way to the green jacket in 2008.
But Spieth showed no signs of faltering as he picked up birdies on the second and fifth to move to 10 under par and four shots ahead of Australian Jason Day, with Ernie Els, Charley Hoffman, Justin Rose and Sergio Garcia another stroke behind.
All eyes were on Rory McIlroy as he began his bid to complete the career grand slam on Thursday, but it was Ryder Cup team-mate Justin Rose who made a flying start to the 79th Masters.
McIlroy is looking to join Gene Sarazan, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods in winning all four grand slam titles by claiming a first green jacket at Augusta National.
But after a drive of more than 320 yards on the opening hole and an approach to 10 feet, the 25-year-old missed out on a first ever birdie on the first at the 23rd attempt.
The world number one then hooked his drive on the second into the trees and ended up in a narrow creek, but after taking a penalty drop was able to pitch out to the fairway and hit a superb approach to save par.
McIlroy was four shots off the early pace being set by American Charley Hoffman, who had hit the first shot of the tournament at 7:45am - following the traditional opening ceremony - and was four under par with two holes to play.
Gary Player was able to claim bragging rights after joining Jack Nicklaus and Arnold Palmer in getting the 79th Masters under way on Thursday.
The trio formerly known as golf's 'Big Three' - they have 13 Masters titles between them - continued their role as honorary starters by each hitting a tee shot on the par-four first hole.
And it was 79-year-old fitness fanatic Player who produced the longest drive by around 10 yards from 75-year-old Nicklaus, who recorded his first ever hole-in-one at Augusta National during Wednesday's par-three contest.
Both men split the fairway on a hole ranked the third hardest on the course last year, but 85-year-old Palmer - who has been struggling with a shoulder injury which kept him out of the par-three contest - hooked his shot a short distance towards the ninth fairway.
With that the trio retired to the clubhouse and allowed the tournament proper to begin, with conditions perfect for the early starters.