Dustin Johnson claims second win of the season at the FedEx St. Jude Classic

MEMPHIS, Tenn. -- Dustin Johnson emphatically clinched the victory on Sunday, holing out for eagle from 170 yards on the final hole for a six-stroke victory in the FedEx St. Jude Classic.

"What a cool way to end the day," Johnson said.

Johnson shot a 4-under 66 for his second PGA TOUR victory this season and 18th of his career to take back the No. 1 ranking he held for 64 straight weeks before dropping down a month ago. He won the event for the second time, finishing with the eagle, three birdies and a bogey for a 19-under 261 total.

Andrew Putnam started the final round with a share of the lead for the first time in his career. He shot 72 and finished at 13 under.

Preparing for the U.S. Open, Johnson took the lead by himself with a par on No. 1, while Putnam double-bogeyed, and cruised to the $1.18 million winner's check. Johnson turned in the lowest score under par by a winner here since David Toms won at 20 under in 2003, and that was before the course was redesigned with par dropped from 71 to 70 after the 2004 tournament.

Johnson, who won the U.S. Open in 2016, heads to Shinnecock Hills after stringing together four straight rounds in the 60s. He went 67, 63 and 65 before wrapping up a final round that felt almost like a practice round with the only question remaining how low Johnson would go.

At least until his dramatic walk-off eagle. Johnson was in the intermediate rough to the right of the fairway, and the ball bounced twice before rolling into the cup to bring fans to their feet.

J.B. Holmes (67) was at 9 under. Stewart Cink (72) and Richy Werenski (71) tied at 8 under. Brandt Snedeker (70) and Retief Goosen (66) tied four others at 7 under.

Phil Mickelson had a 65 and was at 6 under.

Putnam, a two-time winner on the Web.com Tour, had only one bogey through his first three rounds. He pushed his opening tee shot into the right rough and his approach in the rough left of the green. He wound up three-putting for double bogey. Johnson rolled in a four-footer for par and a two-stroke lead at 15 under on a sizzling day with the temperature feeling like 99.

Johnson worked on keeping the ball in the fairway, hitting 3-wood off the tee on the first of the course's two par 5s. Even with the 3-wood, Johnson had the second-longest drive of the day, hitting 333 yards on the 554-yard hole.

Even when Johnson three-putt No. 5 to drop to 15 under, Putnam also bogeyed protecting Johnson's lead at three strokes. Putnam pulled within two strokes with a birdie on No. 7, rolling a putt 11 feet after Johnson parred the hole.

Johnson hit an iron 307 yards off the tee at No. 10 . After hitting iron off the tee at No. 12 and going left of the cart path, Johnson saved par with a 16-foot putt to protect his two-stroke lead. Then Johnson hit a drive 359 yards on the par-4 No. 13, leaving him 95 yards to the pin. Johnson then hit his approach to 3 feet for his second birdie to go 16 under.

He previewed his dramatic finish on the par-5 16th. Johnson's tee shot found the trees right of the fairway, and he threaded a shot through a couple trees to just off the green. He chipped to 5 feet and birdied for a four-stroke lead.