rory mcllroy
Rory Mcllroy announced the worrisome news of his ankle ligament rupture through instagramReuters

Rory Mcllroy, world No. 1 and four-time winner of men's major golf championships, could miss the British Open after he ruptured his ankle ligament while playing football.

The 26-year-old defending champion, who clinched his first Open Championship last summer, took to photo-sharing service Instagram to break the worrying news.

"Total rupture of left ATFL (ankle ligament) and associated joint capsule damage in a soccer kickabout with friends on Saturday. Continuing to assess extent of injury and treatment plan day by day," the Northern Irishman wrote.

"Rehab already started..... Working hard to get back as soon as I can."

McIlroy is now set to have further scans on his ankle over the next 48 hours and he has not ruled himself out of the Open, a spokesman for the golfer told the BBC.

However, if the injury is serious, he could also miss the chance to defend his US PGA Championship title in mid-August.

The 2015 Open Championship will be held from 16 to 19 July at Old Course at St Andrews in Fife, Scotland. It will be the 29th Open Championship to be played at St Andrews.

The last time the Open was held at St. Andrews in 2010, when Mcllroy posted scores of 63-80-68-69 to finish third. 

The golfer was supposed to play in the Scottish Open this week in preparation for the Open, but now the tragic incident has made his participation uncertain. 

McIlroy, who turned professional in September 2007, has had a mixed season so far, finishing fourth at this year's Masters back in April and joint ninth at last month's US Open; both the tournaments were won by Jordan Spieth, ranked No. 2 in the world.

He missed the cut at the Honda Classic in March, but won the World Golf Championships Match Play and the Wells Fargo Championship in May.

The Northern Irishman joined Tiger Woods and Jack Nicklaus as the only players to have won three of golf's modern majors by the age of 25.  He also became the youngest major winner after Tiger Woods when he won the US Open in June 2011 when he was 21 years.