Goals from Presnel Kimpembe and Kylian Mbappe left Manchester United with a mountain to climb as Paris Saint-Germain won 2-0 at Old Trafford in the Champions League round-of-16 first leg and Paul Pogba was sent off.
PSG struck twice in seven minutes before the hour, Kimpembe volleying home a corner before Mbappe finished a low cross from ex-United player Angel Di Maria to condemn United caretaker manager Ole Gunnar Solskjaer to his first defeat in charge.
Things became even worse for the home side with the seconds ticking away as Pogba was dismissed after a foul on Dani Alves, meaning he misses the second leg in Paris.
United had been quickly out of the blocks, Marcus Rashford's attempt to play Jesse Lingard through thwarted by an interception, but the first real threat came from Di Maria, whose curling shot after six minutes went wide of David De Gea's far post.
Back came United and Ashley Young fed Rashford, whose deflected cross-shot forced Gianluigi Buffon into a save.
Rashford's sharp turn brought a foul that saw Kimpembe booked before United again threatened when fine play from Pogba ended with a low cross that Buffon held bravely.
A Young cross was diverted away from Lingard and Pogba fired over, with Julian Draxler soon becoming the second PSG player to be booked when he fouled Ander Herrera.
Lingard got his attempted pass to Martial on the left wrong as United failed to make the most of a breakaway chance, and Pogba was then shown a yellow card for a foul on Marco Verratti.
Draxler's touch put Verratti in but he fired wide, and Young fouled Kylian Mbappe to become the fourth player of the night to be booked.
The card collection grew to five when Juan Bernat saw yellow for his clumsy challenge on Young, and then Di Maria rounded De Gea only to scuff a shot at him before his blushes were spared by an offside flag.
Young crashed into Di Maria as he chased a wayward pass, clattering him off the pitch but escaping with a talking-to from the referee.
Solskjaer was forced into a change in first-half injury time when Lingard, who had gone down minutes earlier with what appeared to be a muscle tweak, was replaced by Alexis Sanchez.
A second change followed before the start of the second period, with Martial -- who looked to have strained a hamstring shortly before the end of the first half -- replaced by Juan Mata.
Rashford and Mata created the first opening of the half, the former's cross whizzing through the box, before the bookings tally rose to six when Lindelof fouled Mbappe.
De Gea made a good save from Mbappe's header but, from the resulting corner, PSG took the lead when United left Kimpembe unmarked to volley home.
Young blocked Di Maria's powerful strike following a superb Marqinhos pass, and the visitors were soon a whisker away from a second when Alves' volley was deflected wide.
Herrera's bouncing strike was close as United sought a way back, but on the hour they were in deep trouble when Di Maria provided the perfect cross for Mbappe to steer home.
Dani Alves was booked for a foul on Pogba, but PSG were starting to threaten to run riot and De Gea made superb saves from Martial's dinked shot and Bernat's thumping effort to keep United in the tie.
Luke Shaw's shot was blocked by Alves as the home side regained some composure and began to come forward again, Herrera winning a corner that was wasted.
With 15 minutes remaining, Verratti sprained his ankle and was replaced by Leandro Paredes, and as time began to run out Young broke but no teammate could get on the end of his cross.
Di Maria came off to be replaced by Colin Dagba before Solskjaer made his final change as Rashford made way for Romlu Lukaku.
But United's woes deepened, Herrera booked and Pogba shown a second yellow to see red in the closing moments, and there was still time for Shaw to be booked for a frustrated foul on Alves.