But the Dutch veteran has warned that any acting up won't be tolerated.
"Cassano is a good lad who has certainly found a squad that gives him the opportunity to shine in this new adventure," Seedorf told the Gazzetta dello Sport.
"He immediately put himself at the disposal of the team, is working hard and trying to give his best. He didn't seem lazy at all and did plenty for someone who hasn't played for two months.
"I must say in the two days he has been with us, Cassano has shown he wants to work and that is the key to everything. If this becomes the norm for him, then he can have an important future here at Milan."