Dustin Johnson withdraws from Masters with back injury

AUGUSTA, Ga. -- Dustin Johnson has withdrawn from the Masters after injuring his lower back in a fall at the home he was renting for the week.The world's No. 1-ranked player arrived at Augusta National on quite a roll, having won his last three starts.He never took a shot at the first major championship of the year.Clearly in pain during a limited warmup session, Johnson still intended to at least try to play Thursday. He walked slowly toward the first hole, where he was paired with two-time Mas