English striker Rooney served a suspension after the former Manchester United star was shown a red card in D.C.’s 4-0 home defeat against Los Angeles FC on Sunday (AEDT).
Impact was also without its key forward, Maxi Urruti, who was dismissed in the 0-0 draw at New York City FC on Saturday. Both sides felt the effects of losing their front men and struggled to fashion chances in a cagey first half.
Montreal’s Zachary Brault-Guillard, on loan from French Ligue 1 club Lyon, forced home keeper Bill Hamid into the first serious save after a surging run on 55 minutes.
In response, former Boca Juniors attacker Lucho Acosta twice fired wide as the Red-and-Black pushed forward to break the deadlock.
But defences ended on top at Audi Field with D.C. United moving up to second in the Eastern Conference, while Montreal remains seventh.