After reaching the playoffs last season, the Washington Nationals and Baltimore Orioles both seem highly unlikely to get there again.

After Monday's scheduled opener was postponed by rain, the Beltway rivals begin a three-game series Tuesday night in desperation mode, with the Nationals well behind in the NL East and the Orioles also facing a big deficit in the wild-card race.

Baltimore (73-76) had its already slim chances further reduced with a difficult loss at Tampa Bay on Sunday, with the Rays scoring three runs in the last two innings to rally for a 7-6 victory.

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Closer Zach Britton allowed two runs in the ninth on a homer, triple, single and walk. The Orioles fell to 60-2 when leading after eight innings.

"Gloom and doom, we don't do that," manager Buck Showalter said. "We're going to try and win the rest of our games and make it tough on everybody."

Showalter's club dropped six games behind the second wild card after Houston's 6-3 win over the Los Angeles Angels on Monday.

Washington (78-71) may have had its fate sealed by a five-game skid from Sept. 7-12 that included three home losses to the first-place New York Mets, who own a 6 1/2-game lead in the division. The Nationals have since won seven of eight, however, recording 13 hits in Sunday's 13-3 rout of Miami.

"Obviously, (the deficit) is there," Yunel Escobar, who had four hits with four RBIs, said through an interpreter. "But the less we think about it as a team, the better we have a chance of catching up to (the Mets)."

Tyler Moore added a three-run homer and Bryce Harper went 3 for 4 to raise his MLB-leading average to .343.

Harper is 14 for 27 with five homers and 10 RBIs during a seven-game hitting streak. His 41 homers lead the NL, while Baltimore's Chris Davis hit his MLB-leading 43rd in Sunday's loss and is batting .377 with eight homers and 17 RBIs in September.

Davis is just 1 for 12 with five strikeouts against Gio Gonzalez (11-7, 3.83 ERA), who has done his part to keep Washington in the race by going 2-0 with a 1.47 ERA in three starts this month. The last was one of his best, as the left-hander matched a career high with 12 strikeouts over seven innings in Wednesday's 12-2 win at Philadelphia.

Gonzalez held Baltimore to a run in six innings while exiting with a lead in a 3-2 loss at Camden Yards on July 10. He lost his previous four starts against the Orioles and is winless in seven since a win with Oakland on Aug. 10, 2009.

Matt Wieters is 10 for 17 with a homer against Gonzalez but is hitting .154 with 22 strikeouts in 63 at-bats since Aug. 21.

Harper has never faced Ubaldo Jimenez (11-9, 4.31), who is 5-1 with a 2.61 ERA in seven starts against Washington and 3-0 with a 1.59 ERA in four at Nationals Park. He hasn't opposed them since July 2011 with Colorado, however.

Jimenez yielded four earned runs over 12 2-3 innings in consecutive road wins over Toronto and the New York Yankees before permitting four in five innings without receiving a decision against Boston on Tuesday.

Escobar, hitting .431 with 13 runs scored over his last 12 games, is 8 for 21 with a homer against Jimenez.

Orioles center fielder Adam Jones was out of Monday's starting lineup because of back spasms, but may be able to play this game.