Pioli says the two players were crucial for their restart form.
“Zlatan is a great professional. He teaches the younger players, he's a point of reference for his teammates and is very respectful of roles," Pioli told Milan's sponsor Skrill.
“His secret is his desire to win and always improve."
The coach hailed goalkeeper Donnarumma, who stepped up as vice-captain when Alessio Romagnoli's couldn't play this season.
“Donnarumma is extraordinarily talented and wore Romagnoli's captain's armband with great personality.
“He's one of the strongest goalkeepers in the world and still has sufficient room for improvement."