Rookie Mike Fiers set down the first 18 Cincinnati Reds in order as the Milwaukee Brewers made it two straight over the NL Central leaders 3-1 Tuesday night at Miller Park.   Fiers lost the perfect game and no hitter when Zack Cosart doubled to lead off the top of the 7th.  He would score on a sacrifice fly from Brandon Phillips.  Fiers wound up going eight innings, allowing the one run on three hits with seven strikeouts to improve to 6-4 with a glittering 1.80 ERA.   Aramis Ramirez staked the Brewers to a lead with a two out, two run homer in the first off Johnny Cueto.  Jean Segura would add an RBI in the bottom of the seventh.  Another rookie, Jim Henderson, finished off the ninth to earn his first big league save.  Milwaukee (50-59) will send Randy Wolf to the mound as they go for a sweep of the Reds Wednesday afternoon.