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3/3/2013 4:41 P.M. ET

Detwiler strikes out four, Zimmerman debuts in win

Walters hits walk-off single in ninth after Ramos leads off with double

VIERA, Fla. -- The Nationals had their Opening Day lineup on the field for the first time Sunday and defeated the Cardinals, 7-6, at Space Coast Stadium.

But it was the Nationals bench that won the game in the bottom of the ninth inning, after tying it at 6-6 in the eighth. After Wilson Ramos led off the ninth with a double in his first spring game, Zach Walters singled off Eduardo Sanchez to score pinch-runner Sandy Leon with the walk-off victory.

The game was tied at 5-5 when the Cardinals scored the go-ahead run off left-hander Patrick McCoy in the eighth inning. With runners on first and second, C.J. McElroy singled to right field, scoring Justin Christian.

It was not a good day for Nationals left-handed relievers. They pitched three innings, allowing four runs on seven hits and walked four batters.

But Washington would tie the score in the bottom of the eighth off right-hander Maikel Cleto. Chad Tracy scored on a single by Carlos Rivero.

Before heading off to the World Baseball Classic, Nationals left-hander Ross Detwiler pitched his last game for the Nationals and was solid in his second outing of the spring. He pitched two innings, allowed a run on four hits and struck out four.

The Cardinals scored a run in the top of the second inning. With runners on first and second with nobody out, Christian hit into a double play, but Tony Cruz scored on the play and tied the score at 1-1.

St. Louis then took a 2-1 lead in the third inning, when reliever Craig Stammen allowed a solo homer run to Shane Robinson.

Left-hander Jaime Garcia went three innings for the Cardinals and allowed two runs on five hits, including the tying run in the bottom of the third inning. Ryan Zimmerman, playing his first game of the spring, singled to right field, scoring Jayson Werth to make it 2-2.

The Nationals had a 5-2 lead by the bottom of the six inning. Chad Tracy highlighted the scoring with a two-run homer off Barret Browning in the sixth.

But St. Louis would tie the score in the seventh inning by scoring three runs off left-hander Brandon Mann. McElroy and J.R. Towles highlighted the scoring with RBI singles.

Up next for the Nationals: The Nationals have a scheduled day off on Monday, but return to action on Tuesday against the Astros at Space Coast Stadium. Right-hander Dan Haren will make his second start of the spring. Last week, Haren pitched his first game for the Nationals and went two innings, allowing one run on two hits and struck out three against the Marlins.

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.