Chris Volstad demoted to Iowa

CHICAGO -- The Chicago Cubs' roster shuffling continued Friday when struggling pitcher Chris Volstad was optioned to Triple-A Iowa and catcher Blake Lalli was recalled, perhaps just in time for Geovany Soto to go on the disabled list.

An MRI revealed a slight tear in the meniscus in Soto's left knee.

"It seems to be (a DL situation) but we'll evaluate here sometime after the game," manager Dale Sveum said before the Cubs played the Chicago White Sox Friday.

Officially, Volstad was replaced on the active roster by Lalli, but Travis Wood is expected to assume Volstad's spot in the rotation next week at Houston.

Lalli has played in just 20 games above the Double-A level, all this season at Iowa. He was batting .178 (13-for-73) with three home runs and 11 RBIs.

With Steve Clevenger still working his way back from an oblique strain, infielder Darwin Barney will be the emergency backup catcher behind starter Welington Castillo against the White Sox.

Barney said the last time he was a catcher was in a youth league as a teenager, and even then it was for only two weeks.

Volstad, acquired from the Miami Marlins in the Carlos Zambrano trade, fell to 0-6 after Thursday's 8-7 loss to the Philadelphia Phillies in which he lasted just two innings. He has a 7.46 ERA, and the Cubs have been defeated in all eight of his starts.

Despite shuttling back and forth between the Marlins and the minor leagues for the past four seasons, Volstad still had a minor league option remaining.

Clevenger is expected to go for a rehab assignment in the minor leagues next week.

ESPNChicago.com's Bruce Levine contributed to this report.