Defender Eriq Zavaleta, who started 27 regular season matches and three of Toronto's four previous playoff games, is the odd man out, making room for Marco Delgado to return to the lineup after coming off the bench in the Eastern Conference final second leg against the Columbus Crew.
The Sounders, meanwhile, have benched left back Nouhou Tolo, who had started all four of Seattle's playoff contests. Center back Roman Torres is back in the lineup after being suspended for the Western Conference final second leg versus the Houston Dynamo, with Gustav Svensson moving from central defense to midfield.
Having started as a left winger throughout the postseason, Joevin Jones returns to the left back position he played for most of the regular season.
Toronto XI: Bono; Beitashour, Moor, Mavinga, Morrow; Osorio, Bradley, Delgado; Vazquez; Giovinco, Altidore
Subs: Irwin, Hagglund, Zavaleta, Hasler, Cheyrou, Cooper, Ricketts
Seattle XI: Frei; Leerdam, Torres, Marshall, Jones; Roldan, Svensson; Lodeiro, Dempsey, Rodriguez; Bruin
Subs: Miller, Alfaro, Nouhou, Delem, Shipp, Neagle, Morris