POGBA GOES MISSING
Paul Pogba had led the Manchester United revival with eight goals and five assists since Ole Gunnar Solskjaer was hired as caretaker manager in December.
The stage was set for the Frenchman to reaffirm his place among the world's top players on Tuesday, but instead the midfielder produced an oddly diffident performance that recalled the dark days of the Jose Mourinho era.
The 25-year-old made only 31 completed passes, his fewest in a match under Solskjaer.
In a fittingly downbeat coda, Pogba was sent off just before full-time, catching Dani Alves for a second booking that rules him out of the return leg on March 6.
REALITY BITES FOR OLE
Solskjaer's Midas touch finally wore off a little as the flaws that plagued United under his predecessor, Mourinho, returned to bite the interim boss.
Since arriving to replace Mourinho, the Norwegian had masterminded such a remarkable revival that United headed into Tuesday's game on the back of 10 wins in 11 unbeaten matches in all competitions.
But a host of defensive mistakes and a lack of creativity in midfield showed that the team lacked quality against the top sides in crucial areas.
Paris Saint-Germain duly exploited sloppy defending and United's flat attacking play to seize control.
No Neymar? No Edinson Cavani? No problem for PSG, as Kylian Mbappe rose to the occasion with a blistering display of his electric pace and predatory finishing.
Brazil forward Neymar is out for 10 weeks with a broken metatarsal while Uruguay striker Cavani was sidelined after suffering a hip problem last weekend.
Fortunately for PSG, France forward Mbappe, who has 23 goals in 27 games this season, was simply unstoppable.
United defenders Eric Bailly and Victor Lindelof were brutally exposed by Mbappe's searing pace as he raced clear to meet Angel di Maria's cross with a clinical finish and delivered the killer blow in the 60th minute.