The Rossoneri beat the Blaugrana 2-0 in the first leg at San Siro, and Platini revealed his doubt about a Catalan comeback while praising Juventus’ rise to prominence over the past 18 months.
"I’ve followed Juve for years, they are very strong, and I like their national identity," he said to La Gazzetta dello Sport. "Sometimes they are playing with as many as nine Italians.
"[Juventus legend Gianni Agnelli] would have loved it. In the Champions League, if Barcelona exits, it will be wide open."
The UEFA chief also defended the competition’s formula before reiterating his doubts that the 2011 European champions can recover the last-16 bout.
"I've democratized it. In my day there were teams that played in three finals in a row, but now it’s changing," he added.
"It may even happen that Milan sold [Zlatan] Ibrahimovic and Thiago Silva and are without [Mario] Balotelli but can beat Barca. It will not be easy to recover the 2-0 loss, even for the Blaugrana."
AC Milan heads into the Tuesday night’s clash at Camp Nou on the back of a 2-0 victory at Genoa, while Barca hosts Deportivo La Coruna on Saturday night with the hope that it can turnaround a poor run of form that has seen it lose three of its last four games.