Svilar had made his first team debut four days earlier at the Algarve Stadium as Benfica eased past Olhanense in the Portugal Cup.
But this was a totally different atmosphere and it will not be a game the Belgian will want to remember as he gifted the visitors the only goal of the game.
Benfica had started brightly and had matched José Mourinho’s men in the opening forty-five minutes.
Svilar had looked unsure from set pieces all night and was almost beaten direct from corners by Rashford. Twenty minutes after the interval Rashford floated a free-kick towards the goal and Svilar back pedalled so far, that in catching the ball he proceeded to cross the goal line.
It was a sad way to decide what proved to be a dreary contest that left Manchester United top of the group on nine points whilst Benfica remain pointless.
To compound Benfica’s misery skipper Luisão received his marching orders in stoppage time for a second yellow after lunging at substitute McTominay.
At the final whistle, Lukaku spent several moments encouraging young Svilar, who is a compatriot of his, and perhaps could still go on to be a team-mate in the Belgium senior national team.
If he does, he may will remember Lukaku’s kindness.
The match between Juventus and Sporting in Turin was preceded by a minute’s silence in memory of the victims of the fires in Portugal.
The Juventus stadium turned out the lights, with a flag of Portugal emerging in the darkness and the stands were surrounded by green and red lights.
The silence was interrupted by applause in honour of the victims.
Sporting were a goal to the good after just twelve minutes through an Alex Sandro own goal but the home side levelled matters on the half-hour mark through Pjanic.
The Italians dominated large periods of the game but struggled to break down their opponents and Juve finally netted the winning goal late on thanks to Mario Mandžuki.
FC Porto lost away by the odd goal in five against RB Leipzig with all the goals coming in the first-half.