CHICAGO -- Billy Hamilton drove in Chris Heisey with a go-ahead single in the ninth inning, and Devin Mesoraco followed with a grand slam as the Cincinnati Reds beat the Chicago Cubs 6-1 in the opener of a three-game series at Wrigley Field on Monday night.

Hamilton, who went 2-for-5 and scored two run, skipped a base hit up the middle to drive in Heisey from second with what proved to be the winning run off Cubs reliever Hector Rondon (1-2).

Rondon then loaded the bases for Mesoraco, and the Reds catcher launched a 1-0 pitch into the left field basket for his second grand slam of the season. Mesoraco homered for a fourth consecutive game.

Reds reliever Jonathan Broxton (3-0) worked the eighth for the win, and Logan Ondrusek pitched a 1-2-3 ninth.

The Reds (38-37) earned their third consecutive win and moved over the .500 mark for the first time this season. The Cubs (31-43) lost their third game in a row.

Cincinnati starter Alfredo Simon took a shutout into the sixth inning, but he lost a 1-0 lead when Cubs first baseman Anthony Rizzo slammed a solo home run to left-center with one out in the sixth, his 16th homer of the season.

Simon limited Chicago to five hits, one walk and one run while striking out five in seven innings.

Cubs starter Jeff Samardzija departed after six innings of one-run ball. He gave up four hits, walked two and struck out seven while throwing 107 pitches.

Reds third baseman Todd Frazier went 3-for-5 and collected his 300th career RBI with a first-inning triple. Mesoraco reached base five times: two walks, two hit-by-pitches and the grand slam.

Rizzo finished 2-for-4.

Hamilton, the Reds' center fielder, dribbled a grounder to right field and stretched it into a double to open the game. Frazier then tripled to the wall in right-center, scoring Hamilton for a 1-0 Reds lead.

In the third, Frazier was caught trying to stretch a single into a double after Cubs right fielder Ryan Sweeney fired to second baseman Darwin Barney for a successful tag.

NOTES: Monday's game opened a 10-game road trip that takes the Reds to Chicago, San Francisco and San Diego before returning home for an 11-game homestand heading into the All-Star break. ... The Reds won five of their past seven series. ... Reds RHP Homer Bailey (8-7, 4.68 ERA) takes on Cubs RHP Jake Arrieta (3-1, 1.98 ERA) in Tuesday's middle game of the series. ... Despite losing two of three last weekend to the Pirates, the Cubs have still won four of their last six series dating back to June 3. ... Cubs RHP Jeff Samardzija (2-6) is the only pitcher in the majors to make at least 15 starts and have only two wins despite an ERA below 3.00 (2.60).