Per Buster Olney and his baseball sources, Red Sox third baseman Kevin Youkilis will begin his rehab assignment sometime over the next two days.

Update: WEEI's Alex Speier says Youkilis will take three at bats with the Pawtucket Red Sox on Wednesday.

Youkilis has been on the disabled list with a back injury since April 29, making yesterday the first day he was eligible to return. Still, the team has taken it slow, and it seems now that he will be unlikely to make his return to the active roster before the end of the week.

It's not known how long Youkilis will stay in the minors before making his way back to the major league squad, but since his return will force the Sox into making a decision about their hot-hitting replacement in Will Middlebrooks, they may feel safe in taking their time. When Youkilis eventually does return, it seems likely that Middlebrooks will be on the way down, given Bobby Valentine's comments on the pointlessness of keeping a prospect around to ride the pine.