The Sox dropped Fabio Castro off the 25-man roster and called up Alan Embree.
UPDATE, 10:51 p.m.: As Embree is not on the 40-man roster, a spot will have to made. It could well be Castro, that is not clear at the moment.
The Sox will then have to create another roster spot when Matsuzaka comes off the disabled list on Saturday. Presumably that would be a pitcher and with three lefties in the bullpen, Scott Schoeneweis could be the one.