In mid-November, the Soviet 37th Rifle Corps shifted to the left flank of 46th Army and, together with 23rd Rifle Corps, forced their way over the Csepel island, Hungary, (also known as the Csepel Dunaág river or KisDuna, an anabranch of the Danube) on the night of21/22 November. Their objectives were to destroy the Axis defenses between the Csepel Dunaág and the Danube, to present a direct threat to southern Budapest, to subsequently force the Danube and to get into the flank of the enemy troops defending the city. They crossed at night along a front of about 20 kilometers, without any artillery preparation to assure surprise. On the front line of the Hungarian 3rd Army, the Soviet 316th Rifle Division crossed around midnight. The Soviet troops quickly pushed back the elements of 1st Hussar Division defending the area toward the west and northwest. The Axis positions a line of trenches along the riverbank - were protected by minefields, barbed wire, and electrically charged fences although very few Hungarians actually manned them. As the Soviets secured bridgeheads along the western bank of the river, their artillery crossed over as well and the defenders observed 30 Soviet AFVs that had come over the river.

Since the island had to be taken very quickly, 46th Army placed considerable firepower at the troops' disposal. Landing craft of the Danube Flotilla brought a large number of 45mm anti-tank guns and mortars across to Csepel Island to directly support the first echelon infantry. Artillery firing over open sights and regimental (120mm) and battalion (82mm) mortars played the main role. During the morning hours, elements of the Soviet 316th Rifle Division reached the southern part of Szigetszentmiklós and also broke into Tököl. As a result of this powerful Soviet blow, the Hungarian 1st Hussar Division disintegrated. Hungarian troops established an improvised blocking position which temporarily halted the Soviet advance. Axis artillery, located on the Danube's west bank and on Csepel, brought the blocking position's forward edge under fire. In late morning/early afternoon, the 22nd SS Cavalry Division took over command of the defensive position.

At 1140, the division ordered the four Italian-made Ml5/42 of the 12th Police Panzer Company to Csepel as well. The 316th Rifle Division advanced south of the railroad to occupy Point 102. The Germans counterattacked with two battalions supported by the 10 newly-arrived light tanks and tank destroyers; the Soviet attack stalled and their troops went over to the defensive. In the evening hours, a German-Hungarian counterattack tried to retake the blocking positions in the wooded terrain. Elements of the 17th SS Cavalry Regiment and Hungarian 1st Hussar Division ejected the Soviets from the southern half of Szigetszentmiklós in violent urban combat and reached the railway again. In the evening, without the SS militia, three Hungarian battalions continued to fight along the railroad, where the front line temporarily stabilized. German-Hungarian aircraft flew a total of 150 sorties, mainly against Soviet supplies arriving on Csepel.