Marcus Rashford scored the winner as Manchester United sealed all three points against Benfica in Lisbon.
Rashford's free-kick from all of 40 yards sailed over everyone in the crowded penalty area and into the hands of 18-year-old shot-stopper Mile Svilar.
But it was a nightmare moment for Svilar, who carried the ball over his own line to gift United a goal and the points.
It was an otherwise uneventful 90 minutes, with Eduardo Salvio having the pick of the chances for the hosts.
Here are five talking points...
1. SLOW UNITED FAIL TO IMPRESS
It took United 32 minutes to register their first chance, a header over the bar from Marcus Rashford from a Daley Blind cross.
It was indicative of United's overall insipid display, one lacking in any cutting edge or sense of urgency.
Their passing was ragged throughout and there was little understanding between their attacking players, with only Rashford providing any kind of spark going forward and providing the sense of urgency United needed.
2. MKHITARYAN LUCKY TO KEEP HIS PLACE
After a slow start to his United career, Henrikh Mkhitaryan made himself a permanent fixture in the side, but he has regressed this season and is lucky to still be holding down his place.
Here he was at his infuriating worst, sloppy in possession, poor-decision making - particularly when he sliced a shot wide just before half-time rather than squaring the ball - and lacked the guile needed to play the No.10 role effectively.
3. UNITED BADLY MISS POGBA
This was the seventh game United have been without the injured Pogba and games like this show just how important the £89million midfielder is to Mourinho's team.
Bringing them a different dimension when he is the team through his vision, execution of passing and energy in the middle, in particular his surging runs from deep that can spark an attack in an instant.
Pogba cannot return soo enough for United.
4. RASHFORD UNITED'S MATCH-WINNER AGAIN
As he has been so often this season, Marcus Rashford was United's match-winner again, his fierce dipping free-kick proving too much for Benfica's teenage goalkeeper Mile Svilar, who caught the ball but carried it back over his line.
The 40-yard free-kick was reminiscent, in terms of its delivery, to Rashford's goal that secured United a 1-0 win in their Europa League semi-final first leg at Celta Vigo, en route to winning the competition.
5. BENFICA'S TEENAGE KEEPER MAKES HISTORY
At 18, Svilar made history by becoming the youngest goalkeeper to play in the Champions League, eclipsing the record previously held by legendary former Real Madrid keeper Ikar Casillas, that had stood for 17 years.
But his big night will be remembered for all the wrong reasons, marred by a gaffe which cost his side the game, as he caught Rashford's free-kick but ended up taking it back over the line.
