Dustin Johnson sailed off to the Bahamas for a private celebration of winning his first major championship at the U.S. Open.

He came roaring back at the Bridgestone Invitational.

In the toughest conditions at Firestone in nearly a decade, Johnson made it look easy Sunday when he closed with a 4-under 66 and rallied from a three-shot deficit against the world’s No. 1 player to win another World Golf Championship.

He needed some help from Jason Day, who collapsed on the back nine. Johnson did his part, making a tough par save on the 15th hole when he got in range and pouring in a 15-foot birdie putt on the 17th hole that made a bogey at the end meaningless.

Two starts, two victories, and now No. 2 in the world.

“It’s the first time I’ve won two tournaments in a row. I mean, that’s big,” Johnson said after his one-shot victory over Scott Piercy.

“I’m excited and looking forward to going over to the British with the golf game in good form.”

He looks like the player to beat at Royal Troon with a frightening combination of driving, wedges and — finally — getting some putts to fall.

Day also was looking forward to the British Open, anything to take his mind off the finish. He had a one-shot lead and didn’t hit a green in regulation over the last six holes. Far more damaging was the par-5 16th hole.

He tried to play it safe off the tee on the 655-yard hole and hooked a 3-wood into the trees. He blasted through the branches and across the fairway, getting a good break when a young fan picked up his ball because it allowed Day a free drop from behind a tree.

Then, he tried to squeeze a shot from 200 yards around the pond. It came up short and rode the collar of the bank into the water, leading to double bogey.

“I thought I had the right play,” Day said. “I was just trying to hit it up there to the left, get it just left of the bunker or just in the bunker there. … Sometimes you take those risks and it doesn’t pay off. So it happens, but I’m looking forward to the Open.”

Day rushed over to Johnson before signing his card to congratulate him.

Piercy nearly overcame back-to-back bogeys, but two good looks at birdies burned the edges on the 16th and 17th holes, and a birdie on the closing hole made the deficit one shot and made Piercy a runner-up for the second straight week. He tied for second behind Johnson in the U.S. Open at Oakmont.

“Inch here or inch there is kind of the difference between winning and finishing second or third,” Piercy said.

Johnson joined Tiger Woods as the only players to capture three of the four World Golf Championships. He won the Cadillac Championship at Doral last year, and the HSBC Champions in Shanghai in the fall of 2013.