Cardinals manager Oliver Marmol said Monday that Matz (back) will throw a "light" bullpen session Wednesday, John Denton of MLB.com reports.
Matz began playing catch last week following a pair of pain-killing injections in his lower back and he's almost ready to starting throwing off a mound at low intensity. The left-hander still looks to be several weeks away from a potential return from the 15-day injured list.