Michael Simpson made 50 saves, J.R. Avon scored twice and the Peterborough Petes are one win shy of an Ontario Hockey League title after defeating the London Knights 5-3 on Wednesday.
Donovan McCoy, Owen Beck and Avery Hayes, with an empty-net goal, also scored for Peterborough.
The Petes have won three in a row in the best-of-seven championship series since dropping the opening game.
Denver Barkey, Sam Dickinson and Easton Cowan replied for London.
Zach Bowen stopped 27-of-31 shots and Owen Willmore saved both shots he faced in 7:09 of action.
Game 5 will take place Friday at Budweiser Gardens in London, Ont.