Cubs 13, Pirates 9: Anthony Rizzo homered twice and drove in six runs as host Chicago rallied from a 6-1 deficit to beat reeling Pittsburgh.

Rizzo delivered a grand slam off Jared Hughes (2-2) during a five-run sixth as the Cubs jumped ahead 10-9. His two-run homer in the fifth began the comeback. Jeff Beliveau (1-0) got the final two outs of the sixth to earn his first major-league victory.

Pittsburgh’s Pedro Alvarez hit his 28th and 29th homers -- a two-run homer in the fifth and a three-run shot in the sixth – and drove in five runs. Rod Barajas hit a two-run homer, his 10th, for the Pirates, who dropped to 73-72 and have lost 12 of their past 15 games to fall three behind St. Louis in the wild-card chase.

Chicago starter Chris Volstad allowed six runs in 4 1/3 innings as the Pirates built a 6-1 advantage. Joe Mather’s fifth homer of the season, a solo homer with one out in the fifth, started a four-run inning that brought the Cubs within 6-5.

Alvarez’s second homer made it 9-5 in the sixth before the Cubs scored five in the bottom of the frame. Darwin Barney hit a RBI single to left before Rizzo’s grand slam to right-center on a 3-1 pitch.

GAME NOTEBOOK: The two teams combined for 29 hits (Chicago 15, Pittsburgh 14). … Cubs LF Alfonso Soriano finished with three hits and two RBIs. … The Cubs have won seven of their past nine, with five of those victories coming against the Pirates.