The Serie A giants have lost two of their first three games, both of which were at home, and the latest setback to Atlanta only served to intensify mutterings regarding the Tuscan's perilous position in charge.
Il Diavolo are still reeling from the loss of key duo Zlatan Ibrahimovic and Thiago Silva to Paris Saint-Germain in the summer, and injuries to the remaining personnel severely harmed their chances of making a good start.
"Allegri is absolutely not up for debate. He has to be calm," Galliani told Sky Italia.
"Now we need to focus on getting our injured players back to full fitness and come back winning in the Champions League.
“President Berlusconi asked me to stay close to the team and calm them at this time.”