Andrey Alexeev and Eric Locke responded for the Spirit (0-1-0).
Anthony Stolarz made 24 saves for the win as Jake Paterson took the loss after allowing five goals on 29 shots through two periods of action. Nikita Serebryakov replaced Paterson to start the third and stopped all nine shots he faced in relief.
London went 1 for 7 on the power play while Saginaw failed to score on four chances with the man advantage.
The Knights lead the series 1-0 and will host Game 2 on Sunday Mar. 24th at the Budweiser Gardens.