Finland struck first, but the Latvian team hauled themselves back into contention with an equaliser before the Finns finished strongly to seal their second win from two games with two more goals.
Latvia's chances were hit early in the game with an injury to key player Lauris Darziņš, which compounded the troubles in the locker room even before the game had started.
In the last game of the group on February 13, Latvia will play Slovakia.