On the winger's botched penalty, the 67-year-old added: "Lookman was not supposed to take that penalty, he is one of the worst penalty takers I've ever seen.
ATALANTA captain Rafael Toloi saw red as the Serie A side crashed out of the Champions League.
Things swiftly went from bad to worse for Gian Piero Gasperini's men, as a disastrous first half saw them fall 3-0 down on the night.
Feeling embarrassed, Toloi got up and begun to charge at De Cuyper, who had turned and was walking away.
"Retegui and De Ketelaere were there, but Lookman in a moment of enthusiasm after scoring decided to take the ball and that was a gesture I did not appreciate at all.
