Sam scored in the 52nd for New York (9-6-6), putting in Mike Grella's lobbed pass. The Red Bulls have a four-game unbeaten streak.
Dominic Oduro scored for Montreal (8-8-4), which lost star defender Laurent Ciman to a second yellow card in the 79th minute. Montreal is 6-1-1 in its last eight home games.
The match marked the return of Red Bulls coach Jesse Marsch, who guided Montreal in its MLS expansion season in 2012, as well as former Impact players Karl Ouimette and Felipe Martins. Felipe hit the post on a last- second free kick.