Dustin Johnson has usurped Jason Day and seized the world No. 1 ranking.
Johnson utterly dominated the Genesis Open Riviera Country Club in Los Angeles, winning by five shots today.
The American knew that he would claim the top billing for the first time in his career if he won the PGA Tour event and Day was sufficiently far back in the field.
Day had a quiet week, finishing outside the top 60 and conceding the world No. 1 rank that he has held since March last year for 47 consecutive weeks.
"He deserves it because he's been playing great golf,'' said Day.
Johnson's response was typically droll. "It sounds good,'' he said.
Day is only the third male Australian — after Greg Norman and Adam Scott — to hold the world No. 1 title. He has been No. 1 for a total 51 weeks in his career.
But his hold on the mantle was loosened when he missed several months of golf at the end of last year because of a back injury.
Day has played four tournaments this season with a best finish of tied-fifth at Pebble Beach.
Adam Scott was the best Australian at Riviera, finishing tied-11th.