The two teams will meet in the Champions League knockouts.
"Of course I know about Fraser," Buffon told the Daily Record.
"I watch all the top young goalkeepers in the world and I'm sure he can become one of them. The top three young goalkeepers in the world for me are Joe Hart, Manuel Neuer and Salvatore Sirigu. It will be one of those three who will go on to be the best in the world.
"But if Forster keeps on playing like he is there is no reason he can't be close to or even in that group.
"In a goalkeeper I don't just look for the great saves but for the authority and confidence he shows. As a goalkeeper you can make only one or two mistakes a season if you want to be the best.
"It's in the big games where you see character because that is where you are most likely to make mistakes. I have seen both games he played against Barcelona now and not only did he make great saves, he looked confident. He didn't look like a goalkeeper who was going to make a mistake."