The former Brazil international believes that the in-form Chile international is "among the five best players in the world in his position"
Ahead of Wednesday's matchday-six meeting in Istanbul, the Turkish champions sit third in Group B with four points, two behind the Bianconeri, meaning only a win will do for Roberto Mancini's men if they are to make the knockout stage.
According to Taffarel, if the hosts are to have any hope of upsetting the Serie A leaders, they have to nullify Vidal.
"Tevez is a very smart Argentine, but Vidal is Juventus' biggest threat," Gala's goalkeeping coach was quoted as saying by Tuttosport.
"He's an amazing midfielder. You cannot afford to lose sight of him. Lose him for one moment and he shows up in front of goal.
"Vidal is among the five best players in the world in his position. He is Chilean, but he would be great for the Brazilian national team as well."
Vidal netted a hat-trick in Juventus' 3-1 win over Copenhagen on matchday five.