It is definitely not the 3rd or 4th largest as both the Hassan II Mosque in Casablanca and the Faisal Mosque in Islamabad are larger in terms of covered area (prayer halls) and their courtyard capacity. Sheikh Zayed Mosque is jockeying for 5th or 6th place with the Badshahi Mosque in Lahore, which continues to have the largest courtyard of any mosque in the world. The covered are of Sheikh Zayed Mosque is larger than that of the Badshahi Mosque but it has a smaller courtyard. For now, it should stay in 6th place until it's area and capacity is proven.