Masters showdown starts with top ranked Dustin Johnson still in doubt
World number one Dustin Johnson was uncertain to play as the 81st Masters began Thursday, swirling winds adding a new twist to an epic showdown at Augusta National.
Northern Ireland's second-ranked Rory McIlroy could be the man who benefits most if Johnson, scheduled for an afternoon tee-off, eventually decides to withdraw after hurting his back in a fall at his rented house on the eve of the tournament.
Australian world number three Jason Day is also among the top rivals expected to challenge for the title along with 2015 Masters champion Jordan Spieth.
Johnson suffered a serious fall on a stairway, according to his agent, but is still hoping to take part in the tournament.
He was expected to visit the PGA Tour's medical trailer Thursday morning for possible X-rays or an MRI exam on his lower back.
The world number one is the odds-on favorite for the Masters after winning three events in a row in a faultless buildup to the first men's major tournament of the year.
But McIlroy, another long-hitter like the 32-year-old Johnson, is seen as a serious threat.
In his ninth Masters, he is seeking to complete a career grand slam at Augusta and hoping to make amends for a Sunday back-nine disaster that cost him the title in 2011.
American Daniel Summerhays struck the first tee-shot on hole number one, the par-4, 445-yard dogleg known as the Tea Olive, at 8 am to launch the tournament on a course rain-soaked from overnight thunderstorms.
Cold and windy conditions, with gusts of up to 40 mph (65kph), were expected to play havoc with the world's greatest shotmakers for the first two days of the 72-hole showdown.
"It's going to be pretty tough -- 20-30 mph winds is not what we're used to around here," Day said.
"And it's going to be cold, so the ball is not going to be flying very far. Typically, I kind of like those tough conditions.
"I'm a grinder in that sense. I need to respect it more and not really be too aggressive."
Spieth says it will take time to sort out strategy.
"It's going to take a good five six holes, I think, before we really understand what this golf course is going to give us," he said.
However, the conditions may suit wily campaigner Phil Mickelson, the five-time major winner who would become the oldest Masters champion just two months shy of his 47th birthday.