A group of different National Federations have expressed interest in hosting the 2025 or 2027 edition of the International Swimming Federation (FINA) World Championships and World Masters Championships, it has been announced.
Five of the Federations have also named the cities they would like to host, but China and Ukraine are yet to make their choices clear.
The other countries are Australia, Hungary, Russia, Serbia and the United States, who have suggested Melbourne, Budapest, Kazan, Belgrade and Greensboro respectively.
A meeting will now be held between the candidates and FINA in January next year in Lausanne, at which all the necessary information regarding the bidding process, will be distributed.
The candidates will then have to decide whether to submit a formal bid, which, if they decide to go ahead, will have to be presented on June 17 next year.
The FINA Bureau are then scheduled to announce the successful candidates on July 11.
The next FINA World and Masters Championships are due to be held in Gwangju in South Korea in 2019, Fukuoka in Japan in 2021 and Doha in Qatar in 2023.
The World Championships and FINA World Masters Championships, an event for competitors aged 25 years old and older, have been held jointly since 2015 when they were staged in Kazan.
If Kazan's bid for either 2025 or 2027, they would join a select group of cities who have hosted the FINA World Championships more than once.
The only other cities to have staged two are Rome in 1994 and 2009, Perth in Australia in 1991 and 1998 and Barcelona, in 2003 and 2013.
Fukuoka is due to join the group when it hosts the 2021 World Championships having already staged it in 2001.
Besides Kazan, Belgrade, Melbourne and Budapest are also bidding to host the World Championships for a second time.
Belgrade was the host for the first-ever FINA World Championships in 1973.
Melbourne had previously staged them in 2007 and Budapest was the host of last year's event.
But there will undoubtedly be strong pressure to choose Greensboro in the US to host at least one of the two editions.
America has never hosted the Championships, despite finishing top of the medals table in 13 of the 17 editions staged so far.