The 37-year-old Ulreich was injured in their 1-1 draw at Bayer Leverkusen on Saturday, picking up an adductor muscle injury, Bayern said in a statement.
He had been called up for action after Urbig's concussion in their midweek Champions League win over Atalanta and amid the ongoing injury absence of first-choice Neuer.
Teenager Leonard Prescott was on the bench on Saturday as he was on Tuesday in Italy, and the 16-year-old could potentially earn a start for Wednesday's return leg against Atalanta, with Bayern carrying a 6-1 win from the first leg. Other options are keepers from the reserve team.
Neuer is working towards a comeback from a muscle injury, but is unlikely to be fit for Wednesday in Munich. Urbig is expected to come back next week.