Manchester United need a miracle to qualify for the next round of the 2018-19 UEFA Champions League.
The Premier League giants were overpowered by Paris Saint-Germain at Old Trafford in the first leg of round of 16.
For PSG, Presnel Kimpembe and Kylian Mbappe scored in the second-half as they won 2-0.
Meanwhile, United's Paul Pogba was sent off after accumulating two yellow cards.
United were forced to substitute both Jesse Lingard and Anthony Martial, due to injuries in the first half and their substitutes couldn't deliver the goods.
PSG broke the deadlock in the 53rd minute with Kimpembe scoring from an Angel Di Maria corner.
In the 60th minute, the sensational Kylian Mbappe then met Di Maria's inviting cross which he put past goal-keeper David de Gea.
United failed to apply any pressure and the defense was exposed by the PSG forwards.
Pogba, who had a frustrating night, received a second yellow card in the final minutes and will now miss the second leg.
They had just one shot on target, which summarizes their performance on a big night at Old Trafford.
United need to achieve the impossible in Paris next.
"Mountains are there to be climbed, you can't lay down and say this is over We will go there, play our game and improve from today. Today is a reality check for us," said United manager Solskjaer.
United's interim boss Solskjaer registered his first defeat in his 12th game in charge across all competitions.
This was United's worst ever home defeat in any European competition.
Mbappe became the third ever player to score in his first three away UCL appearances on English soil.
Di Maria provided two assists in an UCL match for the third time in his career.
"We deserved to win, and to do so here at Old Trafford just now, I congratulate my team - but it's only half-time and we still have to play at the Parc des Princes," said PSG manager Thomas Tuchel.
In the second encounter of last night, Zaniolo scored two goals to give Roma the edge over Porto in their first leg encounter.
The teenager controlled forward Edin Dzeko's pass to drill a low effort past Iker Casillas.
He then went on to add a second from six yards.
But visitors Porto got a crucial away goal via Adrian Lopez.
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