With two on and two out in the Chicago ninth, Anthony Rizzo hit a hot grounder just inside the first base bag. Brandon Belt went to his knees in an attempt to corral the ball, but it skipped past him all the way into the right field corner.
Both runners scored on the play to allow Chicago to overcome a 2-1 deficit and the Cubs held on in the bottom of the ninth. Kevin Gregg worked the ninth for the Cubs and after allowing a leadoff single to Pablo Sandoval he retired three batters in a row to collect his 20th save.
Matt Guerrier (4-4), who retired all four men he faced in the seventh and eighth innings, picked up the victory.
The hard-luck loss went to Sergio Romo (3-5), who put the first two Chicago batters on base in the ninth.