Another victory pulls them closer to an NL Central title.
Carlos Beltran looks to continue pounding the Nationals on Tuesday night and help the Cardinals beat them for a fifth straight time since last fall.
St. Louis (92-65) beat Washington in five games during last year's division series and has won all four regular-season meetings this year.
Opening this three-game set with a 4-3 victory Monday knocked the Nationals out of contention for the two wild-card spots, allowing division rivals Cincinnati and Pittsburgh to clinch.
"It doesn't feel too good," Nationals manager Davey Johnson said. "Now, we're spoilers. So it's not over for us."
Washington should have plenty of motivation in that role since the Cardinals are trying to hold off the Reds and Pirates, leading both by two games.
Beltran will likely play a part in potentially expanding that lead. The right fielder is hitting .415 with five homes, 12 RBIs and 10 runs over his last 11 meetings with Washington, including the postseason.
He had two hits Monday, including a two-run homer to end a season-high 24-game drought.
"I don't think about things like that," said Beltran, who has six RBIs in five games. "It's not about homers. It's about helping the team."
It's unclear if the Cardinals will have Matt Holliday back in the lineup after he missed his second straight game with back spasms.
The left fielder is 13 for 22 with seven RBIs and eight runs in five games, and owns a .371 average over his last 17 regular-season games versus the Nationals.
The last time the Cardinals faced Gio Gonzalez (11-7, 3.39 ERA) was a 9-7 win at Washington in Game 5 of last year's division series.
Gonzalez allowed three runs with four walks in five innings while not getting a decision. He also struggled in a 3-2 win in Game 1, matching his career high by issuing seven walks while giving up two runs in five innings and not factoring in the decision.
Those performances were a tremendous departure from Gonzalez's only regular-season meeting with St. Louis, a five-hitter in a 10-0 win Aug. 31, 2012.
The left-hander enters this matchup winning four of his last five starts with a 1.87 ERA. He earned a 3-2 win over Miami on Thursday, allowing two runs in six innings.
The Cardinals will counter Gonzalez with rookie Michael Wacha (3-1, 3.21), who is facing Washington for the first time.
The 22-year-old right-hander is 1-1 with a 2.38 ERA in four starts since being recalled from Double-A Springfield and inserted in the rotation.
Wacha, though, is 0-1 while allowing six runs and 16 hits with 14 strikeouts in 9 2-3 innings over his last two outings.