Taiwanese right-hander Chien-Ming Wang makes his first game set in DC.
Wang, a two-time 19-game winner with the New York Yankees, had not won in two years until Aug. 9, when he tossed six innings of scoreless one-hit ball in a 3-1 defeat of the Chicago Cubs at Wrigley Field.
Now 31 years old, Wang had last won with the Yankees while going 1-6 in 12 appearances in 2009. He was out of baseball entirely in 2010 and joined the Nationals on July 29.
He won 19 games in 2006 and 2007, then was 8-2 in 2008 when injuries held him to just 15 starts.
In two previous starts with Washington, he'd allowed 12 runs on 15 hits in nine innings while losing to the New York Mets and Atlanta.
This will be his third home appearance of 2011.
The Reds counter with righty Mike Leake, who reached double-digit wins for the first time in his career on Aug. 10.
The Arizona State product, who won eight games as a rookie last season, picked up win No. 10 after scattering 11 hits and allowing two runs in a 3-2 defeat of the Colorado Rockies.
He'd failed in one previous attempt at No. 10, dropping a 4-3 decision to the Cubs after giving up three runs on six hits in six innings.
Leake has won both his career starts against the Nationals and has posted a stingy 0.75 earned run average, while allowing just two overall runs on 12 hits in 12 innings.
The Reds are 4-6 in his last 10 starts.
On Sunday in Cincinnati, James Darnell had two hits and drove in two runs to lead the San Diego Padres past the Reds, 7-3, and avoid a three-game sweep.
Jay Bruce belted a three-run homer for the Reds, who had a four-game winning streak snapped.
Dontrelle Willis (0-3) took the loss after giving up four runs in 2 2/3 innings. Willis left the game in the third after experiencing forearm soreness in his left pitching arm and will be evaluated on Monday.
In Philadelphia, Sunday's rubber game between the Nationals and the Phillies was postponed because of rain.
The contest will be made up as part of a split doubleheader on Tuesday, Sept. 20, at 1:05 p.m. (et).