Taylor Ruck continued her impressive form in the 2018 Mare Nostrum Series with another double win on the opening day of action in Barcelona.
The Canadian teenager followed up her pair of wins in France at the weekend with victories in the women's 50m and 200m freestyle races.
Ruck's time of 24.68 was good enough to take top spot over 50m from Holland's Kim Busch and Russia's Maria Kameneva. In the 200m, she fronted a Canadian top three with her time of 1:56.06 besting Rebecca Smith and Kayla Noelle Sanchez.
Missy Franklin also continued her return from double shoulder surgery and competed in the 200m race, where she finished fifth in 1:59.25.
Yasuhiro Koseki swam a winning time of 59.01 in the men's 100m breaststroke. This time also broke Adam Peaty's Mare Nostrum record of 59.07 set in 2016.
Another Mare Nostrum record fell in the women's 100m backstroke as Kathleen Baker stormed to victory in 58.77.
Brodie Williams and James Guy were the best of the Brits on the first day, with Williams finishing fifth in the men's 200m backstroke (2:01.66) and Guy taking fifth in the 200m butterfly (1:58.96). Guy also had an eighth in the 50m butterfly (24.05).
Laura Stephens and Jessica Fullalove both claimed sixth-place finishes - Stephens in the 100m butterfly (59.58) and Fullalove in the 100m backstroke (1:01.73).
Other British finalists included Craig Benson coming eighth in the 100m breasstroke (1:01.66), Siobhan-Marie O'Connor finishing eighth in the 200m breaststroke (2:28.94) and Duncan Scott taking eighth in the 200m medley (2:04.84).
Women's 800m Freestyle: 1 Erica Sullivan (USA) 8:35.51, 2 Marlene Kahler (Austria) 8:37.63, 3 Giulia Salin (Italy) 8:37.80.
Men's 50m Backstroke: 1 Michael Andrew (USA) 24.70, 2 Benjamin Treffers (Australia) 25.11, 3 Ryan Held (Wolfpack Elite) 25.25.
Women's 50m Breaststroke: 1 Yuliya Efimova (Russia) 30.43, 2 Molly Hannis (Tennessee Aquatics) 30.75, 3 Katie Meili (New York Athletic Club) 31.15.
Men's 50m Butterfly: 1 Andriy Govorov (Ukraine) 23.22, 2 Oleg Kostin (Russia) 23.42, 3 Yauhen Tsurkin (Belarus) 23.52.
Women's 400m Medley: 1 Katinka Hosszu (Hungary) 4:38.32, 2 Zsuzsanna Jakabos (Hungary) 4:40.12, 3 Viktoria Zeynep Gunes (Turkey) 4:40.41.
Men's 100m Freestyle: 1 Katsumi Nakamura (Japan) 48.79, 2 Shinri Shioura (Japan) 48.98, 3 Bruno Fratus (Brazil) 49.21.
Women's 100m Backstroke: 1 Kathleen Baker (USA) 58.77, 2 Mie Nielsen (Denmark) 59.57, 3 Anastasia Fesikova (Russia) 59.91.
Men's 100m Breaststroke: 1) Yasuhiro Koseki (Japan) 59.01, 2 Anton Chupkov (Russia) 59.92, 3 Arno Kamminga (Netherlands) 1:00.08.
Women's 50m Freestyle: 1 Taylor Ruck (Canada) 24.68, 2 Kim Busch (Netherlands) 24.95, 3 Maria Kameneva (Russia) 25.04.
Men's 200m Backstroke: 1 Bryce Mefford (USA) 1:59.18, 2 Radoslaw Kawecki (Poland) 1:59.31, 3 Christian Diener (Germany) 1:59.47.
Women's 200m Breaststroke: 1 Kanako Watanabe (Japan) 2:23.09, 2 Jessica Vall Montero (CN Sant Andreu) 2:25.03, 3 Daria Chikunova (Saint-Petersburg SC) 2:25.04.
Men's 200m Butterfly: 1 Bence Biczo (Hungary) 1:56.70, 2 Viktor Bromer (Denmark) 1:56.92, 3 Nao Horomura (Japan) 1:57.65.
Women's 100m Butterfly: 1 Rikako Ikee (Japan) 56.40, 2 Svetlana Chimrova (Russia) 57.53, 3 Louise Hansson (Sweden) 58.96.
Men's 200m Medley: 1 Gunnar Bentz (USA) 2:00.69, 2 David Verraszto (Hungary) 2:01.23, 3 Kirill Prigoda (Russia) 2:01.61.
Women's 200m Freestyle: 1 Taylor Ruck (Canada) 1:56.06, 2 Rebecca Smith (Canada) 1:57.72, 3 Kayla Noelle Sanchez (Canada) 1:58.49.
Men's 400m Freestyle: 1 Naito Ehara (Japan) 3:48.39, 2 Alexander Krasnykh (Russia) 3:48.65, 3 Henrik Christiansen (Norway) 3:50.10.