A company of the 99th Brigade was attached to the 143rd Home Guard Regiment for operations the next day, and a 250-strong battlegroup was removed from the brigade and subordinated to the Karlovac Corps directly. In the Zagreb Corps area, the HV moved across the Kupa River at two points towards Glina—in and near Pokupsko, using the 20th Home Guard Regiment and the 153rd Brigade. Both crossings established bridgeheads, although the bulk of the units were forced to retreat as the ARSK counter-attacked—only a battalion of the 153rd Brigade and elements of the 20th Home Guard Regiment held their ground. The crossings prompted the ARSK General Staff to order the 2nd Armoured Brigade of the Special Units Corps to move from Slunj to the bridgeheads, as the HV advance threatened a vital road in Glina. The HV 2nd Guards Brigade and the 12th Home Guard Regiment were tasked with the quick capture of Petrinja from the ARSK 31st Motorized Brigade in a pincer movement. The original plan, involving thrusts south of Petrinja, was amended by Basarac to a direct assault on the city. On the right flank, the regiment was soon stopped by minefields and forced to retreat, while the bulk of the 2nd Guards Brigade advanced until it wavered following the loss of a company commander and five soldiers. The rest of the 2nd Guards Brigade—reinforced by the 2nd Battalion, elements of the 12th Home Guard Regiment, the 5th Antitank Artillery Battalion and the 31st Engineers Battalion—formed Tactical Group 2 (TG2) operating on the left flank of the attack. TG2 advanced from Mošćenica, a short distance from Petrinja, but was stopped after the 2nd Battalion's commander and six soldiers were killed. The ARSK 31st Motorized Brigade also panicked but managed to stabilize its defences as it received reinforcements. The HV 57th Brigade advanced south of Petrinja, intent on reaching the Petrinja–Hrvatska Kostajnica road, but ran into a minefield where the brigade commander was killed, while the 101st Brigade to its rear suffered heavy artillery fire and casualties. In the Sunja area, the 17th Home Guard Regiment and a company of the 151st Brigade unsuccessfully attacked the ARSK 26th Infantry Brigade. Later that day, a separate attack by the rest of the 151st Brigade also failed. The HV 103rd Brigade advanced to the Sunja–Sisak railroad, but had to retreat under heavy fire. The Zagreb Corps failed to meet any objective