|WGC-FedEx St. Jude Invitational first-round leaderboard|
|-8 B Koepka (US); -6 R Fowler (US), B Todd (US); -5 S Kang (Kor); -4 M Kuchar (US), C Reavie (US), M Homa (US), J Thomas (US)|
|Selected others: -3 P Mickelson (US), S Garcia (Spa), B DeChambeau (US); -2 S Lowry (Ire), G McDowell (NI); Level J Rahm (Spa); +3 R McIlroy (NI)|
World number six Brooks Koepka carded the joint-best round of his career to open a two-shot lead on day one of the WGC-FedEx St Jude Invitational.
The four-time major champion made nine birdies and a bogey in an eight-under-par 62 at TPC Southwind to lead from Rickie Fowler and Brendan Todd.
Spain's Jon Rahm, in his first event since becoming world number one, finished level par after an opening 70.
Rory McIlroy, who can return to top spot with a win, sits at three over.
The Northern Irishman had five bogeys in Memphis, Tennessee, including three in a row on the front nine.
It was a return to form for Koepka, 30, who has been struggling with a knee injury and has just one top-10 finish this season.
"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," he said.
The American heads into the first major of the year at the PGA Championship next week as defending champion.