Tomori has undergone knee surgery to join Simon Kjaer on the sidelines.
But Massara said: “Tomori's injury is not so serious and he should be back quickly.
"We still think that if there will be the opportunity to complete the defensive department, we will do it but only under the conditions that will allow us to improve the team."
Massara was speaking before defeat to Sassuolo on Monday night.
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