Brooks Koepka launched the defence of his WGC-FedEx St Jude Invitational title in style as he produced a first round 62 to open up a two shot lead.
After firing an early warning shot to the star studded field gathered at TPC Southwind with birdies at each of his first four holes, Koepka made a further five gains and just one bogey to reach eight under par.
Rickie Fowler and Brendon Todd were Koepka's nearest challengers on six under after they both made seven birdies and a solitary bogey in their opening 64s, while Sung Kang was another shot further back in fourth.
Former World Number One Koepka has struggled for form since his stunning three shot victory at this event last year, recording just two top ten finishes in the intervening 12 months as a painful knee injury caused him problems.
Ahead of this week's tournament Koepka said he was starting to see signs that things would soon turn around and that proved to be the case on Thursday as he got off to a lightning-quick start.
After firing birdies at his opening three holes, the 30-year-old made it four in a row with a delightful putt from 23 feet on the fourth green to grab a share of the lead.
A two shot swing followed as Koepka dropped his first shot of the day on the seventh and fellow American Bryson DeChambeau made a birdie at the second - his 11th - to get to five under.
But Koepka bounced straight back, sending his tee shot on the short eighth to six feet and rolling in for a birdie before closing his front nine with another gain, this time from 18 feet, to reach the turn in 30 and join the lead once more.
He took the outright lead for the first time when his birdie effort from just under 20 feet on the 11th curled into the heart of the cup before saving par courtesy of a great third shot at the 12th.
After a terrific approach into the 13th green, Koepka trickled in his eighth birdie of the day to get to seven under, where he was soon joined by Fowler after he chipped in at the eighth for his third birdie in four holes.
But Koepka was soon alone at the top of the leaderboard once again as Fowler finished his round with his only bogey at the ninth.
Koepka gave himself a brilliant eagle chance when he went straight for the front of the green with his approach into the long 16th and landed his ball 13 feet from the cup.
He narrowly missed but tapped in from close range for a birdie to jump to eight under and open up a two shot lead.
The four time Major Champion came agonisingly close to notching another birdie on the 17th but his long putt from just off the green hit the pin and bounced out.
He nearly holed his birdie putt from range on the 18th, too, but had to settle for a closing par after it just missed the hole.
Koepka was pleased with his first round effort, attributing his improvements to the hard work he has put in recently.
He said: "I played good and drove it well, putted well, chipped it well. I did everything very solid.
"I missed it in the correct spots and never really felt like I was having to work too hard out there, so that's a little different than it has been.
"I guess that's why I put in all the work.
"I do feel comfortable in this place, I like it, but at the same time it's the first time I feel like I know where my misses are, I know when the club's in the correct spot, I know when the putting stroke's nice.
"It's all just the work we've put in over the last three weeks of countless hours of beating balls and on the putting green."
Thursday's later starters face a short turnaround after Friday's tee times were brought forward due to the weather forecast. The first groups will get their second rounds under way at 7am local time.
