Antonio Valencia was shown a straight red card as Manchester United earned a hard-fought win in the second game of their US tour.
Valencia, who was wearing the captain's armband as one of 11 United changes for the second-half, clattered into the back of Real Salt Lake's Sebastian Saucedo in the 67 minute.
The referee appeared to have just given Valencia a warning, but after also taking with United boss Jose Mourinho, then proceeded to show the right-back a straight red card.
Mourinho was incredulous at the decision, but when he looks at a replay of Valencia's late lunge, in which no attempt was made to play the ball, he will have no complaints.
United went behind after 23 minutes, but hit back with goals from Henrikh Mkhitaryan and a first for Romelu Lukaku since his £75million move from Everton.