At an event where some of the world's leading Para swimmers are honing their edges for the Tokyo 2020 Paralympics, Zheng, an S5 swimmer who took gold at the London 2012 and Rio 2016 Paralympics, won the men’s 50 metres backstroke final in 32.48sec.

Second place went to the S4 Czech swimmer Arnost Petracek, who finished in 42.24, with bronze going to Zheng’s team mate and fellow S5 swimmer Yuan Weiyi in 33.55.

Topf, competing in the SM2 category, set a men’s 150m individual medley world record of 3min 23.00sec in the heats before improving it as he took gold in the final in 3:22.21.

Silver medallist Cristopher Tronco of Mexico, also an SM2 swimmer, set an Americas record of 3:48.03, and bronze went to Israel’s SM4 competitor Ami Omer Dadaon in 2:33.63.

Topf was not the only swimmer to set a world record in the morning heats, as Israel's Malyar set a new S7 mark of 9min 44.19sec in the men's 800m freestyle.

Dadoan, who set the first world record of this event at the Schwimm- und Sprunghalle in the Europasportpark yesterday when he broke his own S4 mark for the men’s 200m freestyle, had collected his second gold earlier in the evening in the men’s 100m freestyle, where he finished in 1:20.32.

Japan’s Takayuki Suzuki set an S4 Asian record of 1:21.53 to take silver, with bronze going to Ukraine’s S12 swimmer Yaroslav Denysenko who clocked 52.86sec.

Another Asian record was set in the women’s 50m backstroke final, where China’s S5 swimmer Lu Dong won in 39.13sec.

Second place went to Russia’s S13 athlete Anna Krivshina, who finished in 31.44, and third place to S6 home swimmer Verena Schott who clocked 40.01.

Lisette Bruinsma, one of four Dutch gold medallists from the 2019 World Para Swimming Championships in London, got onto the top of the podium in the first final of the evening as she won the women’s 100m freestyle.

The S11 swimmer clocked 1:06.31, with silver going to China’s S5 swimmer Zhang Li, who finished in 1:20:49, and bronze to Japan’s S13 athlete Ayano Tsujiuchi, who touched in 1:00.35.

Mexico’s Nely Miranda Herrera, competing in the SM4 category, won the women’s 150m individual medley final in 3min 12.42sec.

Russia’s SM3 category athlete Zoya Shchurova took silver in 3:37.27 and bronze went to Turkey’s SM4 swimmer Emine Avcu in 3:34.72.

A total of 340 athletes from nearly 50 countries are due to compete the fourth leg in this year’s World Series, which has also included events in Sheffield in Britain, Lewisville in the United States and Lignano Sabbiadoro in Italy.

Competition continues until Sunday (June 20).

Para swimmers are divided into 10 classes based on degree of functional disability from S1, the most severely affected, to S10, and a formula is used at these event to attribute a points score.