The France international has established himself as a pivotal player for the Italian champions since his free transfer from Manchester United in the summer of 2012.
"Pogba is one of those players that leaves you with your mouth open," Buffon said to Italian TV show Tiki Taka. "After three or four training sessions, we understood his quality.
"We immediately thought if they saw well at Manchester or not because he is truly impressive."
Pogba has scored five goals in 19 league appearances for the Serie A leaders.
The 20-year-old midfielder, who is a reported target of Paris Saint-Germain and has also been linked with a return to the Premier League, is set to extend his contract with the Turin outfit, with his current deal expiring in 2016.