What happened: Dansby Swanson left Sunday's game with left side discomfort after an awkward swing, the Cubs said. The shortstop did not finish the at-bat sequence on the field afterward.

Why it matters: Swanson's exit comes as Chicago carries a 4-2 series edge over the Cardinals into Sunday's finale, a lead St. Louis cut into with an 8-4 win Saturday. Losing the same Dansby Swanson who was swinging a hot bat for the Cubs for any stretch tightens an infield already adjusting to deadline additions Tyrone Taylor, Clay Holmes and Kevin Gausman.

What to watch: Watch for a Cubs update on Swanson's status before Chicago's next game.