Montreal Impact took a step towards the MLS Cup, but a thrilling Eastern Conference final first leg was overshadowed by a pitch embarrassment.
Local boy Patrice Bernier slid through a flawless pass, and Oduro was in on goal to slot a shot past Irwin.
Toronto forwards Sebastian Giovinco and Jozy Altidore have been red hot for the past three months, and the team's defense - led by goalkeeper Clint Irwin -has conceded the fewest goals of any Eastern Conference team this season.
The second leg will be played on Wednesday, Nov. 30, in Toronto.
If a team playing with a three-man defense isn't well-disciplined and aware of their teammates' positioning, they can get roasted down the wings. Seven minutes later, Evan Bush stopped Justin Morrow's low shot from inside the box.
Oduro set Mancosu's scoring play in motion by picking off defender Steven Beitashour's poorly-considered header and passing left to Ignacio PIatti.
U.S. midfielder Bradley lifted Toronto within 3-2 in the 73rd minute, aided by a centering flick from Altidore and a set-up flick by Tosaint Ricketts before his right-footed smash.
Four minutes later TFC was again buzzing inside the Montreal box.
Didier Drogba will leave Montreal Impact at the end of the MLS season.
All three lines of the 18-yard box at one end were drawn about two yards too close to the goal and had to be repainted before the game could begin. That's exactly what happened to Toronto in the first 12 minutes of this game.
The prolific former Ivory Coast global spent nine seasons with Chelsea before moving to the United States, scoring 164 goals across all competitions and leading the Premier League club to their first ever Champions League title.
The second leg will be played next week in Toronto with the victor facing either the Seattle Sounders or Colorado Rapids in the MLS Cup final.
Last year, Toronto FC's first appearance in the playoffs was cut short after Montreal eliminated them in the first round. Both are farther into the playoffs than they've ever been before.With last week's Federation Internationale de Football Association global break, it had been 16 days since either team last played a match.