Soriano was scheduled for an MRI after last night's game.

"How devastating. I mean, leadoff hitter, valuable guy, leads my team in home runs, he's got a lot of energy," Cubs manager Lou Piniella said.

"It's going to be a tough loss."

Piniella said he didn't know what the Cubs would do to fill the hole and would discuss potential moves with general manager Jim Hendry. The Cubs are one game behind Milwaukee in the NL Central.

Soriano singled with two outs in the third inning for Chicago's first hit and then tried to go to third on a single by Ryan Theriot. Soriano pulled up between second and third, favoring his right leg, and tried to hop to third base, where he was tagged out easily. He was then helped off the field and taken out of the game.

"A lot of things go through your mind when one of your best players pulls up like that," Chicago's Mark DeRosa said. "It looked like he was in agony. Obviously someone has to step up. We have to come together and pick up the slack. Hope he gets back as soon as possible. I know it's going to be a while."

Soriano was replaced in left field by Cliff Floyd, who had been playing right. DeRosa went from second base to right and Mike Fontenot entered the game at second.