The 22-year-old Italian shot-stopper was in sensational form for Roberto Mancini's men at this summer's Euro 2020.
Donnarumma denied Jadon Sancho and Bukayo Saka from the spot-kick as Italy defeated England on penalties to lift the Euro 2020 title at Wembley.
The former AC Milan star's sensational performances at the Euros earned him the Player of the Tournament award.
And Donnarumma, who signed for Paris Saint-Germain this summer, was named in UEFA's Team of the Tournament alongside Italy teammates Leonardo Bonucci, Leonardo Spinazzola, Jorginho and Federico Chiesa.
Now, Cannavaro has claimed that "somebody thought he [Donnarumma] was an average goalkeeper" ahead of Euro 2020.
The 47-year-old Italy legend believes that Donnarumma has what it takes to establish himself as the best 'keeper in world football for a decade and beyond.
"I am surprised that, before the Euros, somebody thought he was an average goalkeeper," Cannavaro told Tuttosport.
"There's nothing average in Gigio, just think of the tranquillity he has at 22. He will be the best goalkeeper for the next 10-15 years."
The former Parma star continued: "I am happy Giorgio Chiellini lifted the trophy.
"He was in the stands to watch the 2006 World Cup Final and I played with him too, I really respect Giorgio."
Donnarumma broke into the Milan first team at the age of 16 and made 251 senior appearances during his six years at the San Siro.
The Italy No 1 left Milan this summer and completed a stunning free transfer to PSG.
Donnarumma, who will wear the No 50 shirt at PSG, will challenge Keylor Navas for the No 1 spot in Mauricio Pochettino's first team next season.
However, Antonio Cassano has insisted that Donnarumma is not the world's best goalkeeper due to clubs like Real Madrid and Barcelona not trying to sign him.
Featured Image Credit: PA
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