The Italian defender has hailed the contribution of the Serie A holders' strikers, who both found the net to keep their hopes of lifting the biggest trophy in Europe alive
Ibrahimovic finished well from the penalty spot in the second half as Milan sparked into life following the break. Cassano made the points safe just after the hour when he scored from Ibrahimovic's pass.
Antonini was on hand to review their performance and is upbeat with the rate of progress as his side joined Barcelona at the top of the group.
"It was important for us to win the three points without conceding tonight," Antonini told the press after the game.
"Ibrahimovic? He was fundamental for us and we saw him in action tonight. He was a reference point for us and he made the difference with Cassano."
It was not all one-way traffic for the Italians as Antonini told his colleagues they need to tighten the screws when dealing with pressure.
"We suffered from some of their counterattacks in the first half when we pushed forward, but we did well not to give away a goal," he added.
AC Milan travel to Turin to face Juventus in Serie A on Sunday night.