Duvall, who was called up from Triple-A earlier Monday, snapped a 5-5 tie with his pinch-hit homer off Cubs reliever Justin Grimm (2-4), who surrendered all four runs in one-third of an inning. Grimm started the inning by walking Ivan DeJesus Jr. and then gave up the home run to Suarez that tied it.
The Reds, who entered Monday having lost five of their last six, used the rally to erase a two-run deficit.
Cincinnati tackled on six unearned runs in the ninth off Chicago relievers Travis Wood and James Russell after second baseman Starlin Castro committed two of his three errors in the inning.
