The sixth-seeded Union (11-14-9) was winless in their last seven matches, including a 0-2 loss to the Red Bulls in the final, but eked out a spot in the playoffs for the first time since 2011.
The Union are led by Chris Pontius with 12 goals and six assists.
Starting XI: Blake; Rosenberry, Tribbett, Marquez, Fabinho; Bedoya, Creavalle, Herbers, Barnetta, Pontius; Sapong pic.twitter.com/Lr6m5iBm6s— Philadelphia Union (@PhilaUnion) October 26, 2016
Toronto FC snapped a five-game winless streak with a 3-2 victory over Chicago in the regular-season finale and finished with 53 points, a franchise best.
The third seed in the Eastern Conference, Toronto (14-9-11) has a talented roster with Jozy Altidore, Michael Bradley and Sebastian Giovinco, who leads the team with 17 goals and 15 assists.
"We're going to need guys to make big plays in important moments and we're going to need the fans to make this one of the most special nights in the club's history," Bradley said about the team's first home playoff appearance.
You can watch the match on ESPN2 at 7:30 p.m.