The Romanian, who set the new 100m freestyle world record in Rome, notched another 47 second time to defeat Croatia's Jere Hribar and Cyprus' Nikolas Antoniou.

Popovici touched the wall in 47.13 seconds, which was six tenths of a second slower than the Championship record he clocked earlier in the competition.

His time could barely be matched by Hribar and Antoniou as they set 49.37 and 49.91 respectively.

In his other signature race, the 200m freestyle, the 17-year-old superstar registered 1min 46.18sec to claim gold as well as the Championship record.

Dániel Mészáros of Hungary and Filippo Bertoni of Italy were far off his pace by more than two seconds each, with the former clocking at 1:48.98 and the latter finishing in 1:49.05.

Popovici's third and final gold in the 4x100m freestyle relay where his nation timed at 3:18.84, to defeat France’s 3:20.29 and Lithuania's 3:20.41.

There was also a silver medal in it for Popovici after Romania missed out on gold in the 4x100m mixed freestyle relay by 36 seconds.

Led by Nikolett Pádár, Hungary concluded the race in 3:30.03 to take the gold medal as Italy notched 3:32.54 to settle for bronze.

In fact, Pádár waved goodbye to this year’s competition in style after establishing herself as its most decorated female athlete with five titles.

Her other golds came in the women's 100m, 200m, 4x100m and 4x200m freestyle events at the Videna Aquatic Center.

Poland's Ksawery Masiuk was the most decorated male athlete at this edition's World Junior Championships after accumulating four golds and two bronzes.

The Budapest 2022 bronze medallist set a national and Championship record in the men's 50m backstroke as well as a Championship record in the men's 100m backstroke.

He completed the men's 50m backstroke race in just 24.44, which was 17 tenths of a second faster than South Africa's Pieter Coetze, who claimed silver.

Czech Republic's Miroslav Knedla achieved bronze with a time of 25.18.

The same athletes took the same podium positions for the men's 100m backstroke event but, on this occasion, it was a lot closer.

Masiuk ended the race in 52.91, with Coetze coming eight tenths of a second behind and Knedla following nine tenths of a second later.

Coetze did see gold in the men's 200m backstroke after setting a Championship record of 1:56.05, which proved to be faster than Hidekazu Takehara of Japan and Masiuk.

Takehara clocked at 1:58.22 to win silver before Masiuk touched the wall in 1:58.55 to take bronze.

Portugal's Diogo Ribeiro broke the world junior, Championship and national records in the men's 50m butterfly to claim gold in historic fashion.

The Mediterranean champion registered 22.96 to beat Daniel Gracík, who completed the race in a Czech national record time of 23.46, as well as Dane Casper Puggaard's bronze worthy 23.96.

Merve Tuncel completed a hattrick of gold medals after outpacing Japan's Ruka Takezawa in the women's 400m, 800m and 1,500m freestyle events.

The Turkish swimmer concluded the women's 400m freestyle race in 4:10.29 while Takezawa achieved silver for running 4:11.83.

Italy's bronze medallist Giulia Vetrano was just three tenths of a second away from matching the Japanese athlete.

Tuncel was vastly superior in the women's 800m freestyle, setting 8:30.00, which was roughly six seconds faster than Takezawa and approximately 12 seconds quicker than Spain's Carla Carrón.

Her women's 1,500m freestyle performance was even more dominant, with the Rome 2022 bronze medallist lodging 16:15.95 to win gold.

Takezawa could only notch 16:24.61 while her compatriot Niko Aoki set 16:30.74 to secure third place.

Japan were the overall dominant force after they won 19 medals across the competition, including seven golds, eight silvers and four bronzes.

Hungary and Poland equalled them for golds but fell short on the other colours.

Hungary tallied seven more silver and Poland totalled one silver and six bronzes.