Atlanta (67-81) was eliminated from postseason contention and must win its remaining 14 games to avoid a losing record in four straight seasons for the first time since seven in a row from 1984-90.
Gsellman (7-7) scattered three hits and struck out three for his best outing since June 10, when he pitched 6 2/3 scoreless innings to beat Atlanta.
Julio Teheran (11-12), who had won his previous four starts, allowed two runs, three hits and four walks in six innings. He became the first Braves pitcher since Greg Maddux from 1996-2003 to make 30 starts in five consecutive seasons.