CHICAGO — The Cubs' Geovany Soto, the 2008 NL rookie of the year, is going on the 15-day disabled list with a strained left oblique muscle. Manager Lou Piniella said Soto could be out for a month.

Soto got the injury taking batting practice Wednesday and an MRI the next day revealed the injury.

Soto, who tested positive for marijuana at the World Baseball Classic this spring, is batting .230 with eight home runs and 27 RBIs.

Cubs right-hander Ryan Dempster went on the DL on Tuesday with a fractured right toe, a dugout injury he got celebrating a victory Sunday.

Piniella said the Cubs will likely call up another catcher. Koyie Hill will be the top catcher in Soto's absence.