Leake (14-6) tossed eight innings of shutout baseball as he allowed just five hits while striking out six. A day after Johnny Cueto returned from a long stint on the DL, Sean Marshall pitched for the first time since May and looked solid striking out two in one inning to seal the victory.
The Reds (86-66) jumped all over Jordan Lyles (7-8) as they pounced for four runs in the opening frame. Jay Bruce started the scoring with an RBI single and Todd Frazier followed with one of his own. Zack Cozart drove in a pair to finish the scoring in the first and added another run with an RBI single in the third.
Derrick Robinson, Shin-Soo Choo, and Joey Votto all crossed the plate in the fourth on one swing of the bat by Jay Bruce as he homered for the 30th time this season. He also raised his RBI total to 100 which second on the team to Brandon Phillips' 101. Cesar Izturis added a RBI sac fly in the seventh to complete the scoring.
With the loss the Astros (51-100) become the first team this season to lose 100 games. The Marlins (96) and the White Sox (91) are the only other teams with 90 losses or more.
The win helped keep the Reds ahead of the Nationals (81-70), who have won nine of ten, in the Wild Card race. They also gained ground on the Pirates (87-64) and kept pace with the Cardinals (88-63).
Greg Reynolds (1-2) will start in place of Tony Cingrani in the series finale on Wednesday and will square off against Brad Peacock (5-5). Cincinnati will then have a travel day before finishing its road trip in Pittsburgh.