Cole Perfetti and Bode Wilde scored less than two minutes apart in the first as the Saginaw Spirit held on to down the Windsor Spitfires 4-1 in Saginaw.
Blade Jenkins and DJ Busdeker also scored for Saginaw (28-12-4) in Sunday's OHL game.
Daniel D'Amico had the lone goal for the Spitfires (20-23-3).
The game's top star, goalie Ivan Prosvetov was sensational making 44 saves for the Spirit.
Reagan O'Grady was given a match penalty at 20:00 of the third period, for going after Windsor's Louka Henault.
Windsor will host the first place Knights Thursday at the WFCU Centre, then head back to London Friday.
Although the Spits are only two points back of sixth-seeded Sarnia, and tied for seventh in the Conference with Kitchener, if the playoffs started today, it would be a Windsor/London first round match-up.