Club America took a 1-0 lead in the 11th minute thanks to a Sebastian Caceres strike, and looked odds-on to progress to the CCL final after LAFC's Eduard Atuesta received a red card in the fifth minute of first-half stoppage time.
Atuesta and America goalkeeper Guillermo Ochoa came together after Atuesta appeared to be fouled by Richard Sanchez just prior to half-time. Referee Juan Gabriel Calderon subsequently sent off the LAFC midfielder for the altercation. Tensions flared on the sidelines, and Club America manager Miguel Herrera was also given his marching orders as the two benches emptied.
Play resumed after half-time and the match reduced to a 10-on-10 game after Club America's Luis Reyes also received a red card in the 79th minute.
Latif Blessing capped LAFC's win, scoring in the fifth minute of stoppage time.
LAFC finished with 11 shots, including seven on target, while Club America had 13 shots, with seven on target.
LAFC and Tigres will meet in the final of the CONCACAF Champions League on Tuesday in Orlando, Fla.