Facing Manchester United at Old Trafford, Svilar went down to his right to stop Anthony Martial's 15th-minute penalty to keep the score 0-0.
18y 65d - Mile Svilar is the youngest goalkeeper to save a penalty in a Champions League match (18y 65d old). Wall. pic.twitter.com/LyHgtBWgp0— OptaJoe (@OptaJoe) October 31, 2017
At 18 years, 65 days, the Belgian set the mark just two weeks after making his Champions League debut.
Svilar made history a fortnight ago in the reverse fixture against Man Utd, becoming the youngest goalkeeper to ever start a Champions League match.
Just before half-time, Svilar set another record – this time one of the unwanted variety when Nemanja Matic's long-range shot rebounded off the post, off Svilar's back and in for an own goal.
Svilar moved to Benfica in August after coming up through the Anderlecht youth system.