Arroyo won a career-best 17 games last season and has reached double-digit wins in six of the last seven seasons - including four of five with the Reds since he was acquired from Boston in a trade for Wily Mo Pena in 2007.
He's tumbled to just eight wins in 30 starts so far in 2011, however, and hasn't won a game since a 3-2 defeat of Florida on Aug. 24.
Arroyo is 0-2 with two no-decisions in four subsequent starts, allowing 30 hits and 19 runs in 20 2/3 innings.
He last pitched against Houston on Aug. 1 and got a no-decision in a 4-3 Reds' loss. Arroyo is 11-6 in 27 career appearances against the Astros.
On Tuesday, Devin Mesoraco hit a two-run home run and Jay Bruce added a two- run single as the Reds defeated Houston, 6-4.
Cincinnati starter Homer Bailey (9-7) tossed seven solid innings, allowing two runs on six hits and two walks. He fanned five and added a career-high three hits and a run scored for the Reds, who snapped a four-game losing skid.
Astros starting pitcher Bud Norris (6-11) left the game in the third inning with discomfort in his right shoulder. He went 2 2/3 innings, surrendering three runs on seven hits while walking two and striking out three.
Houston starts lefty Wandy Rodriguez, who's a game under .500 both in his career (73-74) and lifetime against the Reds (7-8), in today's finale.
He last faced Cincinnati on Aug. 2 and took a 5-1 loss after allowing five runs on four hits and three walks in five innings.
Rodriguez is 4-2 in six decisions over eight starts since, including a 9-3 win at Washington on Sept. 10. He got a no-decision in his last start, a 4-3 Houston loss to the Chicago Cubs on Sept. 16.
Cincinnati is 8-6 versus the Astros this season.