Making his third start, Simon (2-1) allowed an unearned run in six-plus innings and sent the Cubs to their fifth straight loss. Simon is in the rotation while Mat Latos recovers from elbow and knee injuries.
Jonathan Broxton pitched a hitless ninth for his second save in two tries, completing a six-hitter for the Reds, who stretched their winning streak to a season-best three.
Jeff Samardzija (0-2) gave up three runs -- one earned -- and six hits in seven innings with seven strikeouts and two walks. He is 0-4 despite a 3.86 ERA in 10 starts since winning at San Diego on Aug. 24.