Cincinnati (12-14) executed its version small ball when Hamilton walked to start the game. He then stole his tenth base in 15 attempts and moved to third on a wild pitch by Jeff Samardzija (0-3). That set up a sacrifice fly by Brandon Phillips to give the Reds a 1-0 lead.
That held until the third inning when Alfredo Simon (4-1) allowed two singles and a walk to load the bases. Starlin Castro brought in two of those runners with a single of his own to make it a 2-1 game in favor of Chicago (8-17). After a double steal put runners at second and third, Simon settled in and struck out Wellington Castillo looking.
Samardzija escaped out of some small jams over the next few innings, but gave up a leadoff homer to Hamilton in the fifth inning. Hamilton's first career homer was a feather in his cap on an evening when he went 3-4 with a walk, a stolen base, and RBI and two runs scored.
The Reds were able to chase Samardzija before the rain chased both teams of the field for the third time. Zack Cozart hit a two-out triple and then an unhappy Simon was pulled for pinch-hitter Chris Heisey, who singled in Cozart for the 3-2 lead. Hamilton reached on an infield single, but Zac Rosscup came on to strike out Joey Votto to end the threat.
After the rain, Sam LeCure worked a scoreless seventh and Logan Ondrusek followed with more of the same in the eighth. Jonathan Broxton continued his success as the Reds closer, working a 1-2-3 ninth for his fifth save in as many chances.
Broxton's role may change in the coming weeks as Aroldis Chapman starts his rehab after taking a line drive off his head in spring training. Chapman is slated to pitch for Single-A Dayton on Thursday. The Reds are also starting rehab for Skip Schumaker in Triple-A Louisville, while Mat Latos draws closer to his return, which also forces manager Bryan Price to make a decision on what he will do with Simon.
The Reds on the current 25-man roster will keep their focus on the Cubs for the final game in a rain shortened series on Wednesday. Edwin Jackson (1-2, 5.02 ERA) will take on Tony Cingrani (2-2, 2.86 ERA) in a rematch of a game won by the Cubs 8-4 on April 19.