Maicon Santos tied it with his team-leading fourth goal to push United’s unbeaten streak to five matches.
But Santos also had a 90th-minute goal correctly disallowed for offsides, one that would’ve given United (2-2-3) their first consecutive wins since the 2009 season.
Instead, the expansion Impact (1-5-2) got their first draw away from home after coming close in one-goal losses at Real Salt Lake and F.C. Dallas earlier this month.
Montreal has played six of its first eight matches away from home. Corradi scored his second goal of the season in the 69th minute, heading Lamar Neagle’s cross from into an open net with goalkeeper Joe Willis stranded at the near post.
Santos took just four minutes to level it, collecting a pass from Perry Kitchen, evading several defenders, and striking a 25-yard shot into the bottom right corner.
United’s several supporters clubs observed a moment of silence during the 12th minute of Wednesday’s match in memory of long-time fan Chico Solares, who died Tuesday.
As the clock rolled into the 13th minute, the same fans erupted into the loudest roar of the half with chants of “Chi-co! Chi-co!,” chants that again resurfaced after the final whistle.