ATLANTA, Georgia (REUTERS) - Justin Thomas, Webb Simpson and Paul Casey tied for the second-round lead as Jordan Spieth slipped four strokes behind at the Tour Championship in Atlanta on Friday (Sept 22).

American Thomas eagled the par-five 18th after hoisting his second shot to five feet for a four-under-par 66 on another benign day at East Lake.

Compatriot Simpson and Englishman Casey carded 67 to join Thomas at seven-under 133, one stroke ahead of a group of four including American Patrick Reed, whose 65 was the best of the day.

Spieth struggled with his long game and only a sublime touch around and on the greens allowed him to limit the damage to a 70.

He leads the season-long FedExCup standings, ahead of second-placed Thomas, and will collect a US$10 million (S$13 million) bonus if he stays on top of the points list after the final round on Sunday.

First-round leader Kyle Stanley set the tone for a frustrating day by lipping out a par putt at the first hole en route to a 73 that left him four shots behind.