The Tour Championship concluded its first round at East Lake in Atlanta with Australian Min Woo Lee emerging as the sole leader.
Lee finished one stroke ahead of fellow Americans Rickie Fowler and Cameron Smith, who both carded scores of -4.
Tommy Fleetwood, the tournament's defending champion from England, posted a four-under 66 to secure his position within the top five field.
Fleetwood's performance places him in contention alongside Lee, while other notable players including Viktor Hovland and Jason Day also finished at -6 and -5 respectively.
Lee's opening round was characterised by a measured approach to the course conditions, allowing him to build a single-stroke advantage over the pack.
While Fleetwood did not extend his lead, his ability to hold steady against the pressure of defending titleholder status has kept him firmly in contention for the final cut.
The event continues through subsequent rounds with the leaderboard subject to further change as players navigate the challenging links at East Lake.
No official results beyond the first round have been confirmed by the governing body responsible for the Tour Championship schedule.