Mikhail Katukov's 1st Tank Army was to form the westward-facing outer encirclement line, while Pavel Rotmistrov's 5th Guards Tank Army would form the inner line, facing the city. A secondary attack to the west of the main breakthrough was to be conducted by the 27th and 40th Armies with the support of four separate tank corps. Meanwhile, to the east and southeast, the 69th and 7th Guards Armies, followed later by the Southwestern Front's 57th Army, were to join the attack.[12]