Sjöström, the reigning world and Olympic 100 metres butterfly champion, arrived in the Hungarian capital having topped the individual standings at the first Champions Swim Series leg in Guangzhou last month.

The 25-year-old world record holder was again impressive today as she claimed gold in the women's 100m butterfly in a time of 56.78sec, the fastest time set this year.

Farida Osman of Egypt took silver, while bronze was earned by Canadian Penny Oleksiak.

Sjöström returned later in the evening and won the 100m freestyle as she charged back from a disappointing opening 50m to edge Denmark's Pernille Blume in 53.03.

Blume was second having finished in 53.40, with Italian Federica Pellegrini taking bronze, a further 0.51 adrift.

Efimova, the controversial Russian who has served a 16-month doping ban, marked her first Champions Swim Series appearance with two titles.

The five-time world champion clocked the fastest time of 2019 so far on her way to victory in the women's 200m breaststroke, touching the wall in 2min 22.52sec.

Hungary’s Eszter Dora Bekesi was second, over five seconds slower than Efimova, while American Katie Meili did enough for bronze.

Efimova then set the quickest time of the year in the 50m breaststroke as he clocked 30.26, half a second faster than silver medallist Molly Hannis of the United States.

Britain's Imogen Louise Clark came through to claim bronze.

Reigning 50m butterfly world champion Ben Proud of Britain demonstrated his prowess in the 50m freestyle, winning gold in 21.52.

Bruno Fratus of Brazil clinched silver in 21.67, while Russian Vladimir Morozov was the recipient of the bronze medal.

Russian Anastasia Fesikova also set a world-leading time of 27.58 to take gold in the women's 50m backstroke.

Georgia Davies of Britain sealed silver in 27.89, while bronze went to Brazil's Etiene Medeiros.

The event concludes tomorrow.