Scottie Scheffler raced into a five-shot lead after round of the Tour Championship at East Lake, on a day which saw Rory McIlroy make four pars on his scorecard for the very first time in his PGA Tour career.
Scheffler, who started the FedEx Cup finale on 10-under par, carded a solid opening round of 65 to move to 15-under par and five shots clear of Xander Schauffele, who carded a steady 66.
The World No.1 finished with three straight birdies to surge clear of the chasing pack as he goes in search of a fifth victory on the PGA Tour this season.
Scheffler picked up his maiden PGA Tour title at the Phoenix Open, before adding victories at the Arnold Palmer Invitational, WGC Match Play and The Masters.
England's Matt Fitzpatrick made the big move of the first round with a superb round of 64 to vault up to 9-under par in third place. Fitzpatrick closed his round in style with a 12-footer for eagle.
Chile's Joaquin Niemann matched Fitzpatrick's round of 64 to move up to 8-under par alongside defending champion Patrick Cantlay, who despite not having his best stuff out there managed to eagle the final hole for a round of 70.
Elsewhere, McIlroy had just four pars on his scorecard for the first time in his PGA Tour career in a rollercoaster round of 67.
McIlroy started with a triple-bogey seven on the first hole when sending his tee shot OB and he then bogeyed the next.
He then birdied the 3rd, bogeyed the 4th, birdied the 5th, chipped in for eagle at the 6th, birdied the 8th and and bogeyed the 9th to go out in 36.
The Northern Irishman calmed things down with two pars on 10 and 11, before going birdie-bogey-birdie-birdie-birdie-par-birdie to the house.
McIlroy finds himself at 7-under par for the tournament as he goes in search of a record third FedEx Cup title.
Open champion Cameron Smith, who will reportedly move to LIV Golf next week, is also on 7-under par alongside Sungjae Im.
The winner of the FedEx Cup this week will walk away with $18 million.
Tour Championship R1 Leaderboard
-15 S Scheffler
-10 X Schauffele
-9 M Fitzpatrick
-8 J Niemann, P Cantlay
-7 R McIlroy, C Smith, S Im