The Bayern Munich legend was stunned by the Juventus skipper's poor performance during die Roten's 2-0 win over the Bianconeri on Tuesday
The Bianconeri skipper was at fault for both goals, failing to change direction in time to keep out a slightly deflected strike from David Alaba, before later spilling a tame Luiz Gustavo shot at the feet of Mario Mandzukic, who immediately teed Thomas Muller up for a tap-in.
Beckenbauer was particularly shocked by the way in which the 35-year-old Buffon was beaten all ends up by Bayern's opener.
"Buffon looked like a pensioner," the Bavarians' honorary president told reporters after the game, according to the Gazzetta dello Sport.
"I don't want to upset you, but he should have saved that shot. Maybe, he was not expecting Alaba to strike it from there: Alaba shot from 120 metres!"
Buffon and his colleagues will now desperately be hoping to make amends in next week's return leg in Turin.