PSG pressured Barcelona throughout the opening minutes but only made it pay from the set piece, when Di Maria lined up a 20-yard free kick and blasted it through the Barcelona wall. It was an isolated opportunity as PSG stopped Barcelona from playing, pressing from the front and nullifying Lionel Messi and Luis Suarez.
No team has ever overturned a deficit of four or more goals to progress in the Champions League knockout stages. "They played better, they were better tactically and they outdid us physically". Conceding a goal at home could spell the end of their hopes.
Each of PSG's three forwards offers something different, and they complimented each other well.
Writing for ESPN FC, French football expert Jonathan Johnson has explained that speaking in the mixed zone after the game, the former Dutch global, when approached on the subject replied; "Messi?"
Barcelona hadn't lost a Champions League contest by a four-goal margin since 2013, when they fell to Bayern Munich in the semi-final.
It was a memorable victory for PSG head coach Unai Emery, who had beaten Barcelona only once before in 23 matches during his tenure in La Liga with Valencia and Sevilla, reports Efe.
But Emery has form in Europe. With a helping hand from Barcelona's lacklustre defence and mis-firing attack, PSG blew their visitors away.
Another superb Di Maria effort from range and a Cavani goal sealed the rout for the hosts. Draxler, who underperformed at Wolfsburg, has excelled since his January move to the French capital.
"His reaction there was poor", Ferdinand told BT Sport.
"Mentally they will go on again and they will believe now they are capable of winning this tournament by beating one of the best teams".
PSG were not finished, however, and with five minutes to go before half-time and with Barcelona begging for a reprieve, Draxler struck beyond Ter Stegen to double their lead after a smart ball from Veratti to put him through.
The result matched Barcelona's heaviest defeat in UEFA competition and leaves Luis Enrique's men needing one of the biggest comebacks in European history if they are to turn the tie round at the Nou Camp on March 8.
German midfielder Draxler on his first season with the French Champions, scored the second for the home side after a brilliant break from the right leaving Barcelona shaken at the stroke of halftime.
It is sure to be one of the toughest tests of Enrique's Barcelona career to date.
Cavani and di Maria both celebrated their birthdays Tuesday in a manner that will endear them to PSG fans for years to game.
"We created great chances tonight and we could have scored more goals but we are satisfied and we will stay grounded".
Barca faced 10 shots on target vs PSG - their joint-highest in a Champions League match since 2003-04 (also vs Bayer Leverkusen in December 2015).