Juggernaut's power comes from Cyttorak. Rip his head off or blow him to atoms, the magic will make him 100% instantly. The only way to stop the Juggernaut is psionics and his armor protects him from that. PIS usually lets everyone and their aunt remove his helmet though, not sure how strong that armor is without PIS involved. Unless Cyttorak falls asleep, Doomsday will be constantly fighting a 100% juggernaut.
note: Rip his head off and blow him to atoms is just a way to explain that his magic keeps him at 100%, im not saying he can be blown to atoms or have his head ripped off.