LAKE FOREST, Ill. — Jason Day’s easy win Sunday at the BMW Championship confirmed what his rivals have known for weeks: He’s the best golfer on the planet.

Day’s mostly stress-free final round of 2-under 69 gave him his fifth win on tour this season, his second in the FedEx Cup playoffs, and vaulted him past Jordan Spieth and Rory McIlroy into the No. 1 spot in the world rankings.

Day, an Australian, zoomed out to a big lead by shooting 61 and 63 in the first two rounds and was never seriously challenged. His 22-under total tied for the second-lowest on tour this year and was good for a six-shot victory over rookie Daniel Berger. Scott Piercy finished third, seven strokes back.

“To be honest, I’ve had terrible sleep over the last few nights thinking about getting to No. 1, thinking about winning this tournament … because I had such a big lead and I didn’t want to give it back,” Day said.

The win also made Day the front-runner in the 30-man field heading into the series finale in Atlanta.

“Whatever Jason Day is doing, or which course he’s playing, it’s ridiculous,” said Danny Lee, who was 19th.

If Day manages a win in Atlanta, it could make the race for Player of the Year considerably closer than anyone expected after Spieth won the Masters and U.S. Open, and appeared to lock up the award.

EUROPEAN: Rikard Karlberg of Sweden beat Martin Kaymer in a playoff to win the Italian Open at Monza for his first Tour victory.

On the second playoff hole at the par-4 18th, Karlberg sunk a birdie putt following an impressive second shot out of the rough.

That came just after Kaymer missed his slightly longer putt.

“I don’t want to win on his mistake, I wanted to do a birdie,” Karlberg said. “To do it against Kaymer is incredible.”

Kaymer, who entered the final round with a share of the lead, also just missed long birdie butts on the 17th and 18th holes in regulation after having wasted a three-stroke lead.