#4 Failure to counter PSG's 3 man defence
Tuchel had studied United well and knew the dangers of that their front three possessed. He tweaked his formation to set up a three-man midfield and as a result, United's dynamic trio suddenly looked blunt. There was very little space for the likes of Martial, Lingard and Rashford to operate from and as the defense stayed deep, United found very little joy in the final third.
Solskjaer definitely saw this unfold as the game progressed, however, he failed to nullify Tuchel's tactics. He did have some options on the bench and could have brought on Lukaku to partner Rashford as a 2 man striking unit to build the pressure on the defense.
Or he could have pulled Martial inside to partner Rashford up front too. The Norwegian could have made a few tactical changes to counter Tuchel's tactics but decided to stick to his plans. Sadly, it backfired as United rarely threatened the PSG defense, who enjoyed a quiet night.