Crystal Palace manager Alan Pardew has admitted the stunner by Alli was hard to watch.
Palace went ahead in the first half due to a Vertoghen own goal, with Harry Kane scoring the equaliser in the second half.
Alli put Tottenham ahead in the second half with a stunning volley late in the second half, with Chadli completing the comeback in injury time.
“It was horrible to watch, and I don’t often say that about a beautiful goal,” Pardew told BBC Sport.
“As soon as he flicked the ball over his head I feared the worst. It was a great moment for him and he is a great talent.”