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The Washington Nationals are struggling to get the clutch game series against the Cincinnati Reds.

Losers of four in a row, the Nationals have gone just 2-for-29 over the last two contests with runners in scoring position. They were 1-for-16 in a home loss to Arizona on Thursday, and last night started a six-game trek with a 1-for-13 effort. All told, the Nats have left 22 men on base in the last two games.

Leake struggled the last time he faced the Nats, on August 16 in the nation's capital. In that game, the righty allowed seven hits and six runs -- five earned -- over six innings to absorb a 6-4 loss.

In his career, Leake is 2-1 vs. Washington, but he's just 2-4 over his last eight outings overall.

Ross Detwiler, who makes his sixth start of the season, has pitched well in his previous two outings. The Washington left-hander has given up a run in each of his previous two starts, covering 12 2/3 innings. On Monday, he threw 6 2/3 frames in a victory against Arizona.

Detwiler has dropped his only two starts against the Reds. That includes an August 17 appearance when the Nationals suffered a 2-1 loss at home.

The Reds have a chance to move to .500 tonight for the first time since July 6.

Cincinnati moved a step closer to the break-even mark with a 4-3 victory last night. Miguel Cairo knocked in the winning run in the bottom of the ninth inning with a single into the left-center field gap.

"I always give myself a chance every time I go to the field," Cairo said. "I prepare myself physically and mentally and that's what you can ask for yourself. When I go out there, I expect to win. I play to win, and I play hard."

Drew Stubbs ripped a one-out single off Collin Balester (1-2) to begin the rally and Todd Frazier followed with another hit to put the winning run in scoring position and set the stage for Cairo's walkoff winner.

Francisco Cordero (5-3) allowed a runner to reach second in the top of the ninth, but worked out of trouble to earn the win.

Starter Dontrelle Willis worked seven innings in a no-decision, but collected three hits for the Reds, who have won 10 of their last 15 games.

Wilson Ramos accounted for all of Washington's runs with a three-run homer, and Ian Desmond added two hits for the Nationals.

"We had runners in scoring position, just didn't swing the bats good," Nats manager Davey Johnson said. "It's a tough loss."

With four games remaining on the month, the Nationals are 11-12 in August. The Nationals, who relocated to DC in 2005, have yet to register a winning August. The Montreal Expos, however, posted a winning record in each of their final two Augusts, going 15-13 in 2004 and 16-13 in 2003.

Washington took two of three from the Reds last week.