For all PSG's injury problems, a double blow also rocked United in the seconds before half-time and at the break as Jesse Lingard and Anthony Martial limped off to be replaced by Alexis Sanchez and Juan Mata.
"It's a reality check for us", Solskjaer, who had gone 11 matches unbeaten before last night's defeat, said. "Our players are disappointed after the game, of course, but I also think they know that we need to step up our level to get to the level that we want to get to".
He has netted eight times and registered five assists in the Premier League since then, though was given his marching orders late in the second half against PSG as the French champions dominated the first leg to bring a two-goal lead back to Paris.
United have already been outclassed at home by one of the best teams in Europe this season when Juventus beat them 1-0 in the group stages.
"I don't think they are good enough to win the Champions League irrespective of what has happened in the last few weeks".
"I can't do anything about Alexis Sanchez", said the Norwegian. They did not have a central defensive partnership of the quality of Thiago Silva and Kimpembe, a midfielder of the quality of Marco Verratti or even Marquinhos, or a player with the speed, skill and strength of Mbappe. "I think that it is over at 3-0".More news: Man Utd and PSG charged by Uefa after Champions League tie
More news: Newborn Found in Middle of Road
More news: Kate Miller-Heidke will represent Australia at the 2019 Eurovision Song Contest
The Red Devils have a tricky-looking fixture list before they travel to the Parc des Princes in Paris, however, with an FA Cup trip to Stamford Bridge to face Chelsea and a visit from Premier League title-chasing rivals Liverpool to come first, as well as league fixtures against Crystal Palace and Southampton.
"If you tease him then it does not make him weaker", said his manager Thomas Tuchel.
Kimpembe, who scored his first senior goal in Manchester, admitted that it was a dream-like scenario for him - even if he was fortunate to escape a second yellow card in the first half.
"Man United played at home and had one shot on goal in a Champions League game - that tells you the difference between the two teams".
"We had many midfielders and we are used to playing with more forwards so we had to adapt".
PSG have struggled on the road in the Champions League against elite opposition but showed little sign of nerves as they stroked the ball around confidently.