Mason Greenwood came off the bench to score in the 85th minute and snatch victory for the Red Devils.
United are now equal with Tigres in their group, with both clubs on four points. They played out a 2-2 draw in the opening round on Sunday.
Only the top team from each group will advance to the semi-finals.
The second-placed team with the best goal difference will also advance, which means United's final group game against Higashi Fukuoka is pivotal to their success in the tournament.