Tommy Fleetwood, the defending champion of the PGA Tour Championship, posted a four-under par 66 on Monday to place himself within contention for the season-ending event at East Lake in Atlanta.
The Englishman's performance marked his first round of eight under par, matching his best score recorded on the PGA Tour during this year's tournament.
Australia's MW Lee leads the field by two strokes with a bogey-free 62, having carded his lowest total to date in the competition.
Norway's Viktor Hovland, who won the FedEx Cup last year, sits three shots behind Lee, alongside American duo Collin Morikawa and Chris Gotterup.
Northern Ireland's Rory McIlroy finished at eight under with a 68 after an inconsistent opening four holes that included two bogeys before he recovered on the back nine.
Scotland's Robert MacIntyre reached three under par, highlighted by an eagle made from over 30 feet on the sixth hole.
England's Justin Rose and Alex Fitzpatrick both completed their rounds at eight under with a score of 68, while none of the 29 players in the field went over par.