Men's 200m Freestyle
· James Guy (GBR) is the defending world champion in this event, having won it at age 19 in Kazan two years ago. The Briton was the first teenage world champion in this event since 2001, when Ian Thorpe (AUS) won at 18.
· Guy was the first swimmer representing Great Britain to win a world or Olympic title in this event and the first in any men's freestyle event since 1908.
· In the Olympic final in Rio last year, Guy finished fourth place. Distance specialist Sun Yang (CHN) won the gold to give himself at least one major title (world or Olympic) in the men's 200m, 400m, 800m and 1500m freestyle.
· The last time the world championships were staged in a post-Olympic year, in 2013, the reigning Olympic champion, Yannick Agnel (FRA) was crowned world champion.
· This event has been won by five different swimmers at the last five world championships.
· The last swimmer to retain his world title in this event was Michael Phelps (USA), who retained the crown he won in Montreal in 2005 in Melbourne in 2007.
· Swimmers representing the United States have won 28 medals in this event at world championships and Olympic Games combined, 16 more than any other nation.
· At world championships alone, team USA has collected 15 medals (G6-S7-B2) in this event, 10 more than the next most prolific country, Australia on five.
· The world record in this event stands at 1:42.00 and has belonged to Paul Biedermann (GER) ever since the 2009 World Championships in Rome.
Women's 1500m Freestyle
· Katie Ledecky (USA) is hoping to win a record third world title in the women's 1500m freestyle, after winning this event in both 2013 and 2015.
· She currently shares the record of two with Hannah Stockbauer (GER, 2001-2003) and Kate Ziegler (USA, 2005-2007).
· Ledecky is the world record holder in the 1500m freestyle as she won the 2015 world title in 15:25.48.
· Only in 2009, a woman representing the United States failed to reach the podium of the 1500m freestyle as Alessia Filippi (ITA) won ahead of Lotte Friis (DEN) and Camelia Potec (ROU).
· Boglárka Kapás (HUN) claimed the bronze medal at the last world championships. She is hoping to become the first woman to finish on the podium in this event in front of a home crowd since Li Zunaxu (CHN, bronze) in Shanghai in 2011.
· The only woman to win the 1500m freestyle world title in front of a home crowd was Filippi in Rome in 2009.
· Mireia Belmonte (ESP) is aiming to become the first Spanish woman to claim a medal in this event at the world championships. She finished in fourth place in this event in 2015.
Men's 100m Backstroke
· The world record in the men's 100m backstroke was not actually recorded in this distance, but in the opening leg of the men's 4 x 100m medley relay in the Olympic final in Rio last year. Ryan Murphy (USA) posted that mark.
· Murphy also claimed the gold medal in this individual event at the Rio Olympic Games, ahead of Xu Jiayu (CHN) and countryman David Plummer (USA).
· The defending champion from Kazan in 2015 is Mitchell Larkin (AUS) who joined Matt Welsh (AUS) as the two Australian world champions in this event. Welsh won his title in 2001.
· No swimmer has won this event at back-to-back world championships since Aaron Peirsol (USA) won it three times in a row (2003, 2005, 2007).
· Peirsol and Roland Matthes (GDR) are the only swimmers who have won this event more than once at world championships.
· Larkin succeeded Matthew Grevers (USA), who had won this event in 2013. Grevers was 28 years and 126 days old when he won it and is the oldest world champion in this event.
· Swimmers from United States have won this event on seven occasions, four times more often than the next most prolific country, East Germany on three.
· Hungary has won two medals in this event, a bronze medal by Tamás Deutsch (HUN) in 1994 and a bronze for László Cseh (HUN) in 2005.
Women's 100m Breaststroke
· Yuliya Efimova (RUS, 2015) and Ruta Meilutyte (LTU, 2013) could join Luo Xuejuan (CHN, 2001-2003), Leisel Jones (AUS, 2005-2007) and Rebecca Soni (USA, 2009-2011) on a record two world titles in this event.
· All three women won their titles in back-to-back editions, a feat which Efimova could repeat.
· Efimova also claimed two silver medals in this event, in 2009 and 2013. Only Jones (5, G2-S2-B1) has bagged more medals in this event at the world championships.
· Meilutyte still holds the world record in the 100m breaststroke (1:04.35). She set this time in the semifinals en route to her world title at the 2013 world championships.
· Lilly King (USA) won the women's 100m breaststroke at the Rio 2016 Olympic Games. She can become the third woman to win the world title in this event as the reigning Olympic champion. Meilutyte won in 2013 after claiming the gold medal in 2012 and Ute Geweniger (GDR) in 1982 after her Olympic title in 1980.
· Katie Meili (USA) claimed the bronze medal at the Olympic Games in Rio de Janeiro. The last time two US women reached the world championships podium in this event was in 2009 when Soni finished first and Kasey Carlson (USA) third.
· Shi Jinglin (CHN) just missed out on a medal at the Olympic Games last year as she finished in fourth place. She could become the second Asian woman to win the world title in this event after compatriot Luo Xuejuan (2001 and 2003).
· The last Asian woman to finish on the 100m breaststroke podium at the world championships was Ji Liping (CHN) as she claimed bronze in 2011 in front of a home crowd in Shanghai.
Women's 100m Backstroke
· Reigning world champion in the women's 100m backstroke, Emily Seebohm (AUS), is hoping to become the second woman to retain the world title after Ulrike Richter (GDR) who won the first two editions in 1973 and 1975.
· Natalie Coughlin (USA) is the only other woman to win the women's 100m backstroke multiple times at the world championships as she won in 2001 and 2007.
· Seebohm also claimed a silver (2013) and bronze medal (2009) in this event at the world championships. She could equal Coughlin (G2-B2) on a record four medals in the women's 100m backstroke.
· Katinka Hosszú (HUN) won this event at the Rio 2016 Olympic Games. She could become the third woman to win the women's 100m backstroke world title as the reigning Olympic champion. Missy Franklin (USA) won in 2013 after winning Olympic gold in 2012 and Coughlin won in 2007 after her Olympic title in 2004.
· Hosszú could become the third woman from Hungary to claim a world championships medal in this event, after Krisztina Egerszegi (HUN) and Tunde Szabo (HUN) who finished first and second respectively in 1991.
· Hosszú is hoping to win the women's 100m backstroke world title in front of a home crowd, making her the second swimmer to achieve this after Zhao Jing's (CHN) victory in Shanghai in 2011.
· Hosszú can become the second woman to win a world title in both a backstroke and individual medley event, after Kristin Otto (GDR) who won the 100m backstroke in 1982 and the 200m individual medley in 1986.
· Kathleen Baker (USA), silver medallist in this event at the Rio 2016 Olympic Games, is hoping to become the sixth US woman to win the 100m backstroke world title, after Franklin (2013), Coughlin (2001, 2007), Lea Maurer Loveless (USA, 1998), Betsy Mitchell (USA, 1986) and Linda Jezek (USA, 1978).
· Fu Yuanhui (CHN) shared the third place with Kylie Masse (CAN) in this event at the Rio 2016 Olympic Games. She could join Zhao and He Cihong (CHN, gold in 1994) as the only medallists from China in the women's 100m backstroke.
· Canada has not seen a woman reaching the 100m backstroke podium at the world championships since Cheryl Gibson (CAN) in 1978 (bronze). Nancy Garapick (CAN, bronze in 1975) and Wendy Hogg (CAN, bronze in 1973) also claimed a medal in this event representing Canada.
· The women's 100m backstroke world record has not been improved since 28 July 2009, making it the longest standing world record time in women's swimming. That day, Gemma Spofforth (GBR) won the world title in Rome in 58.12.