The National League Central Division's best team faces its worst Friday at Great American Ball Park, where the first-place Cincinnati Reds host the Houston Astros to begin a three-game weekend series.
The Reds enter with the league's second-best record behind Washington and an 8 1/2-game lead over the second-place St. Louis Cardinals. Meanwhile, the Astros have won just 42 times in 137 games and only 14 times in 69 games on the road.
They trail the Reds by 40 1/2 games.
Texas-born right-hander Homer Bailey gets the call for the Reds with a chance to end a prolonged slump that's seen him win just once since July 20.
The 26-year-old was 9-6 after toppling Milwaukee on July 20, but is just 1-3 in eight starts since while his earned run average has climbed from 3.74 to 4.09.
He showed signs of reversing things in his most recent start against the Astros on Sept. 1, when he allowed just three hits and a run - with nine strikeouts - in eight innings while getting a no-decision in a 2-1 Cincinnati loss.
Bailey is 4-0 in seven career starts against Houston with a stingy 1.29 earned run average in 48 2/3 innings, allowing only 31 hits and striking out 42 batters.
The Astros start 27-year-old Lucas Harrell, who's also seeking a career-best 11th victory.
Harrell has gone 0-1 in three starts since his most recent victory, an eight- inning gem against the Chicago Cubs on Aug. 14 in which he allowed six hits and a run in eight innings.
The last two starts have resulted in no-decisions, though Harrell has surrendered just two runs and nine hits in 14 innings. The most recent was against Bailey and the Reds in the aforementioned Sept. 1 meeting, in which he went seven innings and struck out three.
Harrell is 0-1 in four career games against Cincinnati.
On Wednesday in Pittsburgh, Kevin Correia tossed six solid innings and Brock Holt knocked in a pair of runs to lead the Pirates past the Astros, 6-3, in the rubber match of a three-game series at PNC Park.
Fernando Abad (0-3) was touched for five runs - four earned - on six hits and three walks over four innings for Houston, which lost for the ninth time in 11 games.
Brandon Laird homered in a losing effort.
In Cincinnati, Roy Halladay spun 7 1/3 innings of one-run ball as the Philadelphia Phillies downed the Reds, 6-2, in the finale of a three-game set.
Mike Leake (7-9) was tagged for six runs on six hits and one walk over just 2 1/3 innings to absorb the loss.
Jay Bruce finished with three hits, including a solo home run and two RBI for the Reds, who have dropped eight straight season series against Philadelphia.
Joey Votto stroked a pair of base hits as he returned to the Reds lineup for the first time since July 15 while recovering from a pair of surgeries on his left knee.
"I think it went better than I expected," Votto said. "I was very happy to be back in the lineup and playing again. Unfortunately, it came with a loss."
The Reds won nine of the first 12 games between the teams this season, including two of three when they met in Houston from Aug. 31-Sept. 2. Cincinnati won nine of 15 games against the Astros in 2011.