CHICAGO | A surprising flip-flop of the Cubs' outfield actually worked, but ended prematurely Monday night when Alfonso Soriano limped off with a left hamstring strain in the fifth inning of a 12-4 victory over the San Diego Padres.

Soriano was injured after trying to make a diving catch of Padres starter Clay Hensley's sinking liner to center. After Soriano tried to walk it off, trainer Mark O'Neal was called out to assist.

Soriano limped slightly coming off the field, then gingerly walked down the dugout steps. He was scheduled to undergo an MRI test.

"He strained it when he tried to throw the ball," manager Lou Piniella said. "You don't want to see any of your players hurt. Injuries are part of the game. He gave a heck of an effort."

Soriano's departure forced Jacque Jones to shift to center and ended Piniella's newest lineup experiment. Jones, the regular right fielder, and sometimes-left fielder Matt Murton exchanged positions. Murton also batted cleanup while Thornwood alum Cliff Floyd was on the bench.

Murton drove in two runs with a first-inning single and fifth-inning fielder's choice, while Jones collected a fourth-inning RBI single.

Michael Barrett belted a two-run homer in the fifth -- first by a Cubs position player in six games at Wrigley Field. Mark DeRosa's solo homer in the sixth came three batters before Floyd, who came to replace Soriano, slugged a three-run blast -- this season's first homer by a Cubs outfielder.

Jason Marquis won his first game as a Cub, giving up one run and three hits in six innings.