Lisbon : Manchester United took a huge stride towards the Champions League knockout stages, seeing off an uninspired Benfica 1-0 to make it three wins out of three thanks to a goalkeeping howler.
Marcus Rashford broke the deadlock midway through the second half when an inswinging free-kick from the left was carried over his line by teenage goalkeeper Mile Svilar.
Svilar, who became the youngest goalkeeper to start a Champions League game aged just 18 years and 52 days, caught the ball but in doing so stepped backwards over his line to gift United the lead.
It was a lucky break for the Premier League high-flyers, who, despite dominating possession, had been struggling to create meaningful chances against the Portuguese champions, twice winners of the European Cup.
Benfica showed increased urgency after going behind, bringing on forward Jonas for Diogo Goncalves but they failed to trouble David de Gea in the visitors goal.
Rashford limped off with about 15 minutes to go, replaced by Anthony Martial, who tested Svilar early following an incisive run into the box.
Benfica captain Luisao was sent off in added time afer a lunge at United substitute Scott McTominay to compound the home side s misery.