Gomez is out for a month with a knee setback.
"I feel sorry for the team," Montella said. "Gomez and Giuseppe Rossi are two players who can make the difference when they are at peak physical condition.
"They will be like new signings next season. It's inevitable we will miss them a lot.
"I'm not sure if we will have them playing together before the end of the season.
"We will see, with Gomez at least it is nothing serious. He will give us an added boost when he comes back.
"There is Matri who can come in, and also Matos who is fit and has maybe played less than he has deserved."
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