MLB: Chi. Cubs 11, Houston 4

CHICAGO, Aug. 6 (UPI) -- Mark DeRosa's grand slam homer in an eight-run third inning Wednesday was the big hit in the Chicago Cubs' 11-4 rout of the Houston Astros.

The infielder also hit an RBI double in the second, giving him his highest single-game RBI total (5) this season.

Alfonso Soriano, one of three players with two hits, launched a three-run homer in the third.

Winner Jason Marquis and two others had one RBI for the Cubs, winners in four of their last five games.

Marquis (7-7) surrendered four earned runs and six hits in 6 1/3 innings.

Houston scored on Lance Berkman's RBI single and Carlos Lee's three-run homer, both in the fourth.

Ty Wigginton had three of the seven hits for the Astros, who have lost two in a row after a four-game winning streak.

Losing pitcher Brandon Backe (6-11) was torched for 11 earned runs and nine hits in 3 1/3 innings.