At the World Swimming Championships in Budapest, Hungary, Kregor Zirk set a new Estonian record in the 200 m butterfly with a time of 1.55,62.
However, Zirk's record breaking performance was not enough to earn him a place in the final, with the Estonian finishing in 11th place overall.
Italy's Thomas Ceccon set a new world record of 51.60 seconds to take gold in the final of the men's 100 m backstroke.
In the men's 200 m freestyle, 17-year-old Romanian David Popovici was crowned world champion, finishing in 1.43.21, ahead of South Korea's Sunwoo Hwang in second (1.44.47) and Great Britain's Tom Dean, who took bronze with a time of 1.44.98.
The USA's Katie Ledecky struck gold in the women's 1500 m freestyle, with a swim of 15.30,15. Second place went to Katie Grimes, also of the USA (15.44,89), with Australian Lani Pallister finishing third (15.48,96).
There was further success for the USA in the women's 100 m backstroke, where Regan Smith became world champion with a time of 58.22. Second place went to Canada's Kylie Masse in 58.40 and Claire Curzan of the USA took third in 58.67.
With a time of 1.05,93, Italy's Benedetta Pilatto of Italy took the women's 100 m breaststroke world title by the narrowest of margins from second place Anna Elendt of Germany (1.05,98), who had to settle for the silver medal. Ruta Meilutyte of Lithuania took bronze in 1.06,02.
Before the final:
On the third day of the World Swimming Championships in Budapest, Hungary, Estonia's Kregor Zirk and Aleksa Gold were in action. Zirk set a new Estonian record of 1.56,13 in the preliminary round of the men's 200m butterfly to secure a place in this evening's semi-finals.
Zirk, who shaved 50 hundredths of a second off his own Estonian record, finished third in his heat, behind world record holder Kristof Milak of Hungary and the USA's Trenton Julian. Zirk's time was enough to put him in ninth place overall for the round, while Milak was the quickest in the heats with a time of 1.54,10.
The semi-finals of the men's butterfly will start this evening at 20:35 and can be seen live on ETV2 and ERR's sports portal.
In the women's 200m freestyle, Aleksa Gold finished ninth in her heat with a time of 2.03,46, meaning the Estonian misses out on a place in the semi-finals. Gold ended up in 28th place overall, 4.56 seconds behind the time required to make the last semi-final place. China's Junxuan Yang recorded the fastest time in the heats, finishing in 1.56,58.
Before the race:
Aleksa Gold, who finished 29th in the women's 100m backstroke on Sunday, will compete in the 200m freestyle on Monday. Gold will compete in the fifth heat, which starts at 10.33.
Gold faces stiff competition from Hong Kong's Siobhan Haughey who took home two silvers at the Tokyo 2020 Olympics, and seven-time Olympic medalist Penny Oleksiak of Canada, who will both appear in the same heat as the Estonian.
After finishing 20th in the men's 400m freestyle on Saturday, Kregor Zirk will represent Estonia today in the 200m butterfly. Zirk begins in the fifth heat at 10.52, where he is up against world record holder and home crowd favorite Kristof Milak of Hungary.
Should Gold and Zirk be successful in their heats, they will go on to compete in the semi-finals later today. The women's 200m freestyle semis start at 20.15, while the men's 200m butterfly semi-finals get underway at 20.35.
You can follow the progress of Estonia's swimmers in Budapest live on ETV2 and ERR's sports portal with commentary in Estonian from Helar Osila and Martin Liivamägi.
Editor: Michael Cole