But Reds battled back in their final at-bat against Chicago's Michael Bowden (0-1).
Jay Bruce then tied the contest with another two-bagger, driving a 1-0 pitch to the wall in right-center field for two runs.
After Bruce went to third on an out, Izturis lined a pitch over leaping Cubs shortstop Starlin Castro for the game-winner.
Bruce also socked a solo homer for the Reds, who improved to 7-1 on a 10-game home stand.
David DeJesus provided a solo homer for Chicago, which fell for the seventh time in eight games.