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The St. Louis Cardinals continue their push for the NL Central Division crown on Tuesday night as they continue a three-game series with the Washington Nationals, who have been pushed into a spoiler role.

The Cardinals maintained a two-game edge over the Pittsburgh Pirates and Cincinnati Reds in the division standings with a 4-3 victory on Monday. The Pirates and Reds locked up postseason berths with their respective wins last night as well with the Nationals' setback.

With five games remaining, St. Louis has a magic number of four to secure its first NL Central title since 2009. It is also a half-game back of the Atlanta Braves for the best record in the NL.

"We're very happy right now to have a spot in the playoffs," said Carlos Beltran, who hit a deciding two-run homer in the fifth inning on Monday. "But we're not thinking about that. We want to win our division and that's going to be our main goal."

The Nats would have been happy with a playoff spot. The 2012 NL East champs had won 16 of their first 21 games this month to get back into the playoff race, but it was too little, too late.

"We gave it a good fight, we just came up short," said Nationals manager Davey Johnson, who is set to retire at season's end. "It's going to be a tough haul, but I'm proud of the guys. Now we're spoilers."

That is the mindset Gio Gonzalez will have when he takes the mound tonight for the Nats. He is 4-1 with a 1.87 earned run average over his last five starts and is coming off a 3-2 win over Miami on Thursday. Gonzalez yielded both runs on seven hits and two walks in six frames.

The 28-year-old southpaw is 11-7 with a 3.39 ERA in 31 starts this season and threw a five-hit shutout in his only previous meeting with the Cardinals. That came on Aug. 31 of last year and Gonzalez struck out eight in the 10-0 win.

Michael Wacha gets the call for the Cardinals and faces the Nats for the first time.

The young righty struggled in his last start on Thursday in Colorado, where he was touched for four runs and 12 hits over 4 2/3 innings. Wacha struck out seven in the no-decision, with the 22-year-old 3-1 with a 3.21 ERA in 14 games this season (8 starts).

The Cardinals swept a three-game set in Washington in April and have won five straight in the series.