MRI reveals slight tear in Soriano's right quad
Soriano is expected to miss 2-to-4 weeks. He had an MRI exam Sunday night and did not travel with the Cubs to Houston.
"The latest from the MRI was that there is a small tear in the quad," manager Lou Piniella said before the Cubs lost to Houston 2-1 in 10 innings on Monday. "It's about one centimeter. We think he'll be out four to six weeks. We think it will be around Labor Day. We were expecting this. It could have been worse."
Chicago purchased the contract of infielder Eric Patterson from Triple-A Iowa to fill Soriano's roster spot. Patterson had a sacrifice bunt in his only at-bat on Monday.
Piniella said Soriano wasn't to blame for the injury.
"He does as good a job of stretching as anybody," Piniella said. "It just happened."
Soriano, who signed a $136 million, eight-year contract, is hitting .297 with 18 homers and 42 RBIs.
"It's a loss," Piniella said. "We're going to have to step up. We have a very young club. We'll just see how they respond."
Patterson was batting .299 with 23 doubles, six triples, 14 home runs and 62 RBIs at Iowa. The left-handed hitter, a Pacific Coast League All-Star last season, is the brother of Corey Patterson, who played for the Cubs from 2000-05.
Chicago also put right-hander Wade Miller on unconditional release waivers and designated infielder Brian Dopirak for assignment.
"There's no sense hanging your head," Cubs general manager Jim Hendry said, according to the Chicago Tribune. "We all had a rough night last night. Nobody slept much, but you've got to get up today and get after it. There's no sympathy involved here. We're ready to grind it out, and we've been grinding pretty good the last couple of months here.
"We've got some people that can handle themselves. It'll give [Matt] Murton some more at-bats, and it'll give Patterson a look. He's been playing very well in Iowa, in the outfield, too, and swinging the bat well. [Felix] Pie is getting better, but we're trying to bring up the guys that are hot that might fill the need that we have, so we'll give him the first look."
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.
Information from The Associated Press was used in this report.