By Steve Ginsburg

WASHINGTON (Reuters) - Jayson Werth belted a ninth-inning, walk-off home run to lift the Washington Nationals to a 2-1 victory on Thursday and force a winner-take-all showdown in the best-of-five National League Division Series.

Werth capped his lengthy plate appearance by lining a shot of reliever Lance Lynn into the Cardinals bullpen in left field.

Washington will host the Cardinals on Friday for the right to face the San Francisco Giants in the best-of-seven National League Championship Series.

Adam LaRoche, who entered the game batting .091 in the series, belted a 92-mph sinker from Cardinals starter Kyle Lohse over the centerfield wall in the second inning to give Washington a 1-0 lead.

The Cardinals evened the score at 1-1 the next inning on a sacrifice fly by Carlos Beltran, an unearned run due to an error by shortstop Ian Desmond.

Washington had just two hits prior to Werth's game-winner, and, other than LaRoche's homer, had not had a runner reach second base.

(Editing by Frank Pingue)