Germany's Christian Diener joined three of the biggest names in the sport in winning twice on day two of the International Swimming Federation World Cup in Doha today.
Diener, a 200 metres backstroke silver medallist at the 2014 European Championships, first triumphed in the 50m backstroke final.
He edged clear in the final stages to triumph over one lap in 23.58sec at the Hamad Aquatic Complex in the Qatari capital.
Russian Vladimir Morozov finished a slender 0.13 seconds behind in second place as Brazilian Nelson Silva touched third in 23.72.
Diener then defeated South Africa's Chad le Clos to take his second victory in the 200m backstroke.
He finished in 1min 50.96sec as le Clos tied for second in 0.06 seconds behind, alongside Poland's world short course champion, Radoslaw Kawecki.
Le Clos had won twice by that point in the 200m freestyle and 100m butterfly events.
The South African won the 200m freestyle in 1:44.40 to comfortably overhaul early American leader Tom Shields, second in 1:45.02.
The Netherlands’ Kyle Stolk touched in third place in 1:45.77.
Le Clos then edged out Shields again just 30 minutes later to win the 100m butterfly by 0.13 seconds in 50.17.
Belarus’ Pavel Sankovich was third in 50.79.
نشكر جمهورنا الكريم تشريفنا بحضور منافسات كأس العالم للسباحة فينا أيرويف الدوحة ٢٠١٧ ، منافسات قوية تقام الآن بمجمع حمد للرياضات المائية pic.twitter.com/iGmCMzcHtH— Qatarswimming (@Qatar_swimming) October 5, 2017
Sweden’s Sarah Sjöström also added victories in the 100m freestyle and the 50m butterfly after defeating Dutch rival Ranomi Kromowidjojo in the final of both events.
She won the 50m butterfly in 24.76 to finish 0.49 seconds clear of Kromowidjojo and by 1.11 over another Dutch swimmer, Maaike de Waard.
Sjöström also won the 100m in 51.62, with Kromowidjojo second in 52.19 and another Dutchwoman, Femke Heemskerk, in third.
Hungary's Katinka Hosszú defeated Sjöström in the 100m individual medley in a time of 57.26.
Sjöström took second in 57.60 as Australia's Emily Seebohm was third in 58.59.
Hosszú also beat Seebohm in the 100m backstroke.
She triumphed in 56.27 to her rival's 56.40.
De Waard took bronze in 58.63.
The next leg of the FINA World Cup is due to take place in Beijing on November 10 and 11.