Jason Day as golf’s No. 1? He predicted it, then won BMW Championship

Jason Day first hit balls at age 6 with a 3-wood that his father, Alvin, recovered from a trash heap in Australia. He was breaking par six years later, and at 20 he proclaimed: “My goal is to be the No. 1 golfer in the world.”

Never afraid to reach for the stars, Day can now revel in being No. 1 in his sport.

“Knowing that right now there’s no one on this planet that’s better than me,” he said, “that’s pretty cool.”

Day overtook Rory McIlroy and Jordan Spieth in golf’s official rankings with a virtuoso performance at the BMW Championship at Conway Farms in Lake Forest, Ill. Day essentially won the FedEx Cup playoff event with an 18-under 61-63 start — but don’t tell him that.

He slept terribly after a third-round 69 and did not feel the victory was in hand until he walked toward the 18th green Sunday with a five-shot lead.

“I mean, it was a stressful day,” he said.

You couldn’t tell. When Day made rare mistakes — missing the 16th fairway to the left and hitting into a bunker on 17 — he compensated with his spectacular short game, finishing 22 under par.

“He played exactly how he needed to,” playing partner Scott Piercy said. “Safe, conservative pars and grab a birdie here and there.”

Day has now won four of his last six tournaments — “a dream run,” he said — and heads into next week’s Tour Championship as the favorite to claim the $10-million booty. McIlroy closed with a one-under 70, and Spieth’s putting woes left him shaking his head after he tapped in on No. 12.

“I still am lacking a bit of confidence in my game,” Spieth said.

Day cannot relate, as everything in his life is clicking.

Wife Ellie is expecting their second child, and their 3-year-old son, Dash, practiced his putting stroke on the 18th green while Dad saluted an adoring crowd. Day later praised his coach and caddie since he was 12, Colin Swatton, for walking the entire course before Sunday’s round to analyze the pin positions.

“That’s how you get the edge,” Day said.

He breezed to victory on a gorgeous late-summer day that reminded everyone how wise it was for the PGA Tour, Western Golf Assn. and BMW officials to move the event to Lake Forest.

Some Conway Farms members grumbled about the low scores Thursday and Friday, and WGA President John Kaczkowski sympathized, saying: “It’s their golf course and they hold it very dear. But these guys are phenomenal players and the greens, as I heard all week from the players, were perfect.”

Justin Rose said that Conway Farms, which played to 7,035 yards Sunday, is on the short side.

“But it has other ways to defend itself,” said Rose, who tied for 13th. “If we got more of an autumn, cool week with a north breeze and low humidity for firmer greens, I think this course is plenty tough enough.”

Next year the BMW moves to Crooked Stick, near Indianapolis, and then it returns to Conway Farms in 2017. It goes to Aronimink Golf Club near Philadelphia in 2018, and then to the No. 3 course at Medinah Country Club in Illinois in 2019.

By then, Day might no longer be the best on the planet. Spieth, McIlroy and perhaps Rickie Fowler will have much to say about that.

But you’d be a fool to discount Day, just as some did after his bold proclamation seven years ago.

“It’s OK to dream big,” he said.

tgreenstein@tribune.com

Twitter: @TeddyGreenstein