Final Fantasy 14: Heavensward is gaining ground on World of Warcraft, having reached more than 5 million registered accounts worldwide.
The latest figures suggest that Blizzard Entertainment's behemoth is down to 5.6 million active users following a 44% decline over the last six months.
Final Fantasy 14, on the other hand, is going through a purple patch, having increased its subscriber base by 1 million since February.
The multiplayer online game has been around for less than half the time of the market leader, originally launching around five years ago.
However, new life was injected into the title in 2012 when it was relaunched as Final Fantasy 14: A Realm Reborn. Then Heavensward went live in June.