Mike Smalling's early second winner secured a vital come-from-behind victory over Wolfsburg in a Juan Mata inspired turnaround on a tense European night at Old Trafford.
United had fallen behind in the fourth minute through Daniel Caligiuri's close range finish, but, after man of the match Mata levelled from the spot, the Spaniard set up Smalling for the decisive winner to leave all four Group B sides on three points apiece after Matchday Two.
Having been beaten at PSV on Matchday One, United simply could not afford defeat in this one, but were left fearing the worst when Caligiuri finished off a neat passing move from Max Kruse's incisive through ball after only four minutes.
Wayne Rooney blazed over from close range after good work from Anthony Martial and Memphis Depay headed straight at Diego Benaglio when well placed, before Caligiuri went from hero to villian when he handled Antonio Valencia's cross.
Juan Mata pulled the Reds from the spot ten minutes before the break but the Reds started strongly after the restart and had soon completed the comeback on 53 minutes.
Mata was again at the heart of things, when Bastian Schweinsteiger's mishit dropped to the Spaniard who guided a delicious flick into the path of Smalling to slide in and score.
Old Trafford erupted with joy and relief but Wolfsburg were not going quietly and went close through substitutes Nicklas Bendtner and Andre Schurrle- who lashed an effort dangerously across goal- as they pressed for an equaliser.
Andreas Pereira excelled on his first competitive start against Ipswich and was introduced on the hour mark here, replacing Memphis after the Dutchman had drilled narrowly wide shortly before being booked.
Chances were ultimately few and far between in the closing stages as United looked to consolidate their slender lead, but it was the German visitors who looked the more likely to score in the closing stages.
Ricardo Rodriguez curled a dipping free-kick inches wide on 85 minutes but that proved to be the final opportunity of the match as United held on for an important Group B victory.
In the other match in this group, our next opponents CSKA edged past PSV 3-2 in Russia meaning all four sides are level on points ahead of the third round of matches next month.
United Faithful Man of the Match: Juan Mata.
Overall team performance: 7.5/10