The Chicago Cubs have extended their winning streak, padded their lead in the NL Central and reduced what remains the smallest magic number in the majors.

Addison Russell hit a go-ahead, two-run single with two out in the bottom of the seventh to lift the Cubs to their fourth straight victory, 5-4 against San Francisco. Chicago put together a three-run first, but the offense stalled while the Giants were building a 4-3 lead.

The Cubbies allowed just three hits, the last coming after Hunter Pence smacked a two-run homer in the opening inning. Chicago’s bullpen retired all 15 batters it faced.

The Cubs improved to a major league-leading 86-47 to push 15 1/2 games ahead of the second-place Cardinals in the NL Central. They also cut their magic number to 15.

The Giants are two games behind the NL West-leading Dodgers after falling to a big league-worst 15-28 since the All-Star break.