The visitors went into the game missing two of their front three, with Edinson Cavani ruled out with a hip injury and Neymar a long-term absentee. It set the stage nicely for a battle between the trio's remaining member - Kylian Mbappe - and United's Marcus Rashford, who led the line ahead of Romelu Lukaku. As the game drew to a close, a clear victor had emerged.
Old Trafford was a cauldron of noise when the two teams walked out, and smoke from some red flares still obscured the pitch as the match kicked off. Angel Di Maria, his every touch booed by the home crowd, went close early on, seeing a long-range effort whistle just wide of De Gea's post. After a fairly even opening half an hour, PSG carved the United's defence open. Julian Draxler slipped Mbappe clear through on goal with an exquisite through ball, but the youngster could only fire wide of the target.
United were hit with two injuries just before the break with Anthony Martial and Jesse Lingard both receiving treatment. The Englishman was substituted in first-half stoppage time, coming off for Alexis Sanchez, while Martial lasted until the break when he was replaced by Juan Mata. United seemed to lose their wings with the pacey duo off the pitch, and rarely threatened from then on.
PSG made the breakthrough 10 minutes into the second half - a corner missed everybody except Presnel Kimpembe, who was lurking at the back post, and the French defender had all the space in the world to side foot a volley into the roof of the net. The goal buoyed the visitors, and suddenly they were completely in control. Dani Alves immediately went close with a volley, and minutes later his team had a second. A low cross was fizzed across the six yard box, and Mbappe used his pace to race past Victor Lindelof and pounce on the ball, side-footing it gleefully into the United net.
But PSG weren't finished - they wanted more. Mbappe found himself clear through on goal, but his chipped effort was palmed away by De Gea. Then Draxler got in on the act, surging down the left and flashing a powerful shot across goal. Again De Gea came to the home side's rescue. The second half wasn't even 20 minutes old.
As the second half drew to a close, both sides made substitutions. Di Maria was emphatically booed as he came off for Colin Dagba, before the ineffective Rashford made way for Romelu Lukaku. Just as United thought their miserable day couldn't get any worse, it did. Paul Pogba received a second yellow after clipping Dani Alves as the pair both went for a loose ball. It was a debatable decision from the referee, but its significance remains the same - Pogba will miss the second leg in Paris. United have a mountain to climb heading into the return match, but then, they have been known to pull off the odd European comeback.