AUGUSTA, Ga. (AP) — Strong winds and a fall down a staircase by the Masters pre-tournament favorite could change the complexion of the season's first major.

Dustin Johnson, the world's No. 1-ranked golfer, injured his lower back late Wednesday afternoon in what his agent described as a "serious" fall down the staircase at a home he'd rented for the week. Johnson goes off in the last group for today's opening round, but even the late 2:03 p.m. EDT starting time may not give him enough time to recover.

The weather forecast for the region, socked by powerful storms two of the last three days, calls for cool, overcast skies and steady winds of 20-30 mph, with gusts up to 40 mph.