ESSENDON has suffered a significant blow on the cusp of the season with defender Martin Gleeson to be sidelined for 12-14 weeks.

Gleeson injured his foot landing after a marking contest late in the final quarter in the Bombers' four-point win over Geelong in Colac on Sunday and requires surgery on a broken foot and a dislocation.

General manager of football Dan Richardson said the club remained optimistic Gleeson, 23, could return after the bye in round 13.

"Marty suffered a major fracture to the front of the talus and a minor dislocation to the subtalar joint in his foot," Richardson said in a statement on the club website Monday morning.

"While this is an uncommon injury, we are fortunate he is in the safe hands of our medical team and Mr Andrew Oppy who will conduct the surgery this morning," he said.

"We expect Marty to be sidelined for 12-14 weeks, but through a successful rehabilitation program we believe he could be in a position to return after the bye."

Gleeson has played 69 games for Essendon since making his debut in round one of 2014.