The Reds rode their luck at times against the Columbus Crew on Tuesday night but came out of the first leg of the Eastern Conference final with a 0-0 draw.
They will meet against next Wednesday with the chance to host the last game of the season on the line.
Greg Vanney named an unexpected lineup and formation, switching to a four-man defence with Nicolas Hasler and Marky Delgado out wide in midfield and Victor Vazquez and Jonathan Osorio playing ahead of Michael Bradley.
Toronto started well, passing the ball calmly and taking the sting out of Columbus’ attack without creating many chances of their own.