Dustin Johnson is awarded with a Seersucker jacket after winning the FedEx St. Jude Classic golf tournament at TPC Southwind in Memphis, Tennessee on Sunday. Photo: Christopher Hanewinckel/USA TODAY Sports

Dustin Johnson reclaimed the world number one ranking by cruising to a six-shot victory in the FedEx St. Jude Classic in Tennessee on Sunday.

The 33-year-old, knocked off the top of the rankings last month by fellow American Justin Thomas, mixed three birdies, a bogey and a stunning final-hole eagle to finish on 19-under-par.

It was Johnson’s 18th career PGA Tour victory and his second at the St. Jude Classic, which he also won in 2012.

Johnson finished with a flourish when his 171-yard second shot on the par-four 18th found the bottom of the cup, sending the crowd at the TPC Southwind in Memphis into a frenzy on a sweltering day.

“What a cool way to end the day to hole that shot on 18,” Johnson said. “I knew coming in this week that I was swinging really well and had a lot of confidence in my game. I played really well all week.”

Johnson had led the rankings for 15 months before Thomas took over on May 13, and the win also moved him into second place in the PGA FedEx Cup standings.

Johnson started the day tied with Andrew Putnam, but the 29-year-old American stumbled with a double bogey on the par-four first hole. Although Putnam went bogey free for the final 13 holes, he was unable to match Johnson’s brilliance and finished on 13-under-par.

JB Holmes had five birdies and two bogeys for a final round 67 to end in third place. Stewart Cink and Richy Werenski tied for fourth at eight-under-par.

Johnson will be among the favourites to win the US Open starting on Thursday at the Shinnecock Hills Golf Course in New York, and he is confident of repeating his 2016 victory in the year’s second major. “I feel like my game is in good shape,” he said.

“I’m driving it well, I’m really hitting my irons well, my wedges are really good, so I’m really looking forward to going into next week. I haven’t seen the golf course yet, but I’ll get in 18 holes tomorrow and go from there.”