Massimo Moratti quit Inter on the eve of last night's dire 0-0 draw with Saint-Etienne in the Europa League.
"We are in an emergency situation and playing every three days meant we weren't as sharp as usual," Mazzarri told Sport Mediaset.
Yann M'Vila was added to the injury list this evening with a sprained knee and suspected ligament damage, but Inter are still top of their Group.
"Today we had to change a great deal and considering the situation I think it was a good performance. The important thing was to continue picking up points.
"We are doing well in Europe, even if of course we like to win every game. We had six youngsters on the field against Napoli on Sunday and put in a great performance. Of course I'd love champagne football, but I don't see many doing that nowadays. Saint-Etienne are a team to be respected."
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