Kliment Kolesnikov and Kristof Milak laid down impressive Olympic markers on Wednesday, just two months out from the Summer Games in Tokyo.
Russia's Kolesnikov stormed to victory in the 100m freestyle in a time of 47.37sec.
The 20-year-old from Moscow had already won the 50m backstroke and was part of the 4x100m relay team victory.
Italy's defending champion Alessandro Miressi was second in 47.45sec with another Russian Andrei Minakov in third in 47.74.
"He is impressive, talented," said young French sprinter Maxime Grousset, who was fifth in the final.
However, the Russian is human after all -- 30 minutes later he swam in the 100m backstroke semi-finals but came home 16th and last in 54.86.
"I was just tired. It's something can happen to anybody. It was our common decision with my coach to swim the back as we hoped I could do it," he explained.
"It turned out that I couldn't at that moment. Anyway, we are not giving up the idea for the Olympics but we will have to work more on it."
Hungary's Kristof Milak was equally dominant in the 200m butterfly.
Two years ago at the world championships in Gwangju, South Korea, the 21-year-old had taken Michael Phelps's world record with a time of 1:50.73.
On Wednesday, he clocked 1min 51.10sec, three seconds faster than his closest rival.
"I don't know why but I got really tense in the call room, almost had to throw up," he said.
"This happens sometimes, especially before the 200m fly when I don't feel that I'm in really good shape.
"But in the end it turned out to be 1:51.1, so I cannot complain."
In the men's 1500m freestyle, Ukraine's Mykhaylo Romanchuk won in the season's second best time of 14min 39.89sec.
1. Sophie Hansson (SWE) 1:05.69, 2. Arianna Castiglioni (ITA) 1:06.13, 3. Martina Carraro (ITA) 1:06.21
1. Kira Toussaint (NED) 27.36, 2. Kathleen Dawson (GBR) 27.46, 3. Maaike De Waard (NED) 27.74
1. Mykhaylo Romanchuk (UKR) 14:39.89, 2. Gregorio Paltrinieri (ITA) 14:42.91, 3. Domenico Acerenza (ITA) 14:54.36
1. Kliment Kolesnikov (RUS) 47.37, 2. Alessandro Miressi (ITA) 47.45, 3. Andrei Minakov (RUS) 47.74
1. Kristof Milak (HUN) 1:51.10, 2. Federico Burdisso (ITA) 1:54.28, 3. Tamas Kenderesi (HUN) 1:54.43
4x200m freestyle relay
1. Russia 7:03.48, 2. Great Britain 7:04.61, Italy 7:06.05