Devin Mesoraco hit a grand slam with two outs in Cincinnati's five-run ninth inning, leading the Reds to a 6-1 victory over the Chicago Cubs on Monday night.

Mesoraco went deep for the fourth straight game, driving a 1-0 pitch from Hector Rondon (1-2) into the basket in left-center for his 13th homer. It was Mesoraco's second grand slam of the season and No. 3 of his career.

Billy Hamilton had a tiebreaking RBI single earlier in the inning as Cincinnati won for the sixth time in seven games to move above .500 for the first time this season at 38-37. The winning sequence started when Chris Heisey reached on a pinch-hit single with two outs and no one on base, snapping an 0-for-16 rut.

It was the first homer allowed by Rondon since Aug. 1.

Jonathan Broxton (3-0) pitched a perfect eighth and Logan Ondrusek got three outs, helping the Reds improve to 30-11 against the Cubs over the last three seasons.

Anthony Rizzo hit his 16th homer for the Cubs, who have lost three in a row. Jeff Samardzija pitched six innings of one-run ball.

The Reds got off to a fast start behind Hamilton, who led off the game with a grounder just past second baseman Darwin Barney. The bouncer died in the grass in short right field and the speedy rookie hustled into second with a double, extending his hitting streak to 11 games.

Todd Frazier followed with a drive into the gap in right-center for an RBI triple. But Samardzija buckled down and kept Frazier at third, retiring Jay Bruce and Ryan Ludwick after he hit Mesoraco for the first time with one down.

Ludwick came up again with runners on second and third in the third and flied to the warning track in center for the final out of the inning.

Chicago wasted a prime scoring chance in the fourth. Rizzo reached on a leadoff single before Starlin Castro doubled into the left field corner, putting runners on second and third.

Alfredo Simon then retired three straight to preserve Cincinnati's 1-0 lead. Luis Valbuena flied out to medium right field, Welington Castillo hit a comebacker to the mound and Ryan Sweeney lined out to left.

The Cubs also wasted a leadoff double by Barney in the third. Samardzija broke his bat over his left knee after he popped up a sacrifice attempt.

Simon allowed one run and five hits in seven innings. He struck out five and walked one.

Frazier finished with three hits and Mesoraco reached five times. He was hit by a pitch twice and walked twice before he connected in the ninth.