Manchester United endured a nightmare return to the Champions League as they lost 2-1 at PSV in a match marred by Luke Shaw sustaining a suspected broken leg.
Luciano Narsingh grabbed the crucial goal in Tuesday's Group B opener at the Philips Stadion, compounding Louis van Gaal's misery sparked by Shaw's early exit.
The 20-year-old was on the receiving end of a thumping tackle from Hector Moreno in the 15th minute, subsequently receiving seven minutes of treatment before being withdrawn on a stretcher.
Former PSV star Memphis Depay lifted the sombre mood thereafter with a stunning solo goal against the club he joined United from in the close-season.
But Moreno, having somehow not been penalised after the Shaw incident, levelled on the stroke of half-time before Narsingh headed PSV into the lead after 57 minutes.
United continued to dominate proceedings thereafter, although clear-cut opportunities were few and far between as PSV defended resolutely.
And Phillip Cocu's men were rewarded for their endeavour as the visitors failed to grab an equaliser.
United began confidently in their first group game for two seasons, only to have the wind knocked out of their sails when Shaw was taken off while wearing an oxygen mask following Moreno's challenge.
Referee Nicola Rizzoli surprisingly opted not to give the expected penalty or red card, and PSV almost capitalised as they enjoyed a good spell. Yet United regrouped impressively, with Depay opening the scoring in the 41st minute.
A clever throughball from Daley Blind freed the winger, who superbly jinked his way past Santiago Arias and Jeffrey Bruma before sliding through the legs of Jeroen Zoet.
United twice nearly added to their advantage immediately, Depay shooting just wide before Chris Smalling was denied by Zoet from point-blank range after a marauding run from the back.
PSV continued to look dangerous, though, and levelled when Maxime Lestienne sent in a corner for Moreno to head home via a deflection off Blind.
Depay continued to look a real danger after the break and forced another save from Zoet following a fine one-two with Anthony Martial, who was making his full United debut.
Yet the visitors' dominance in the early stages of the second period didn't lead to a goal, and they fell behind shortly before the hour.
Andres Guardado's stunning pass began a fine counter-attack that ended when Lestienne sent in a pin-point cross for Narsingh to head home.
United's domination of possession was not bringing any real chances, Juan Mata fluffing the best opening when failing to control a stunning chipped pass from Bastian Schweinsteiger, and Luuk de Jong should have made the win safe for PSV eight minutes from time when he fired over from six yards.
That miss would ultimately matter little, however, as the Dutch champions hung on to secure all three points.
