Iniesta pulled up halfway through the first-half of last night's draw with Champions League opponents AC Milan. The injury was later confirmed as a hamstring strain, which will keep Iniesta sidelined for a month.
With Alexis Sanchez already on the medical table, Zubi said: "It's the worst news, for sure. But we have the squad to fix it. I wish the change had been for a tactical question.
"I'm no doctor, it is disappointing what has happened to Alexis, Andres and Pique, but we have a squad for these setbacks."