UPDATE: Rory McIlroy announces he will miss the Open Championship on his Instagram account.

The PGA Tour took a big blow over the weekend. The No. 1 golfer in the world is unlikely to participate in the British Open - the third major tournament of the season - on July 16.

Rory McIlroy won last year's British Open at Royal Liverpool, but it looks like he won't be able to defend his title in 2015 at St. Andrews.

McIlroy announced on Monday morning that he suffered a "total rupture" of his left ATFL (ankle ligament) and "associated joint capsule damage" via his Instagram account. He sustained the injury playing soccer with his friends on Saturday.

"Continuing to assess extent of injury and treatment plan day by day. Rehab already started," McIlroy wrote. "Working hard to get back as soon as I can."

CNN reported this morning that McIlroy has a "10% chance" of playing in the British Open. Dr. Peter Larkins, a former Olympic steeplechaser, told BBC Sport there's a chance McIlroy misses an extended period of time.

"It's six weeks wearing a moon boot and six weeks of physio," he said.

"Could he play at the Open? It's a tricky one. It depends how much pain he can tolerate. If the ankle is very loose and badly swollen, I can't imagine him walking around for miles for four rounds.

"The swelling can ease in a week with plenty of therapy, but that won't leave much time for practice."

Dr. James Gladstone, the co-director of sports medicine at Mt. Sinai Hospital, appeared on The Golf Channel's "Morning Drive" on Monday and said the "general timetable" for return could range from 10 days to six weeks.

McIlroy was scheduled to play in the Scottish Open this week, which would have been his first event since finishing tied for ninth place in the U.S. Open on June 21. The 26-year-old has finished in the top-11 in his past seven events, including victories at the WGC Match Play in April and the Wells Fargo Championship in May. He also finished fourth at the Masters and tied for eighth at the Players Championship.

Rory's victory at the British Open last year won his father, Gerry McIlroy, $171,000. Gerry placed a bet ten years prior at 500/1 odds that Rory would win the British Open before he turned 26 years old. The Northern Irishman also became the first European player to capture three different majors with the victory.

However, it appears McIlroy will miss this year's event and perhaps a few more. He'll hopefully be ready for the PGA Championship at Whistling Straits, which begins on August 13.