Xin and Lin will both take home a gold medal as they clocked 35.86sec in a dramatic final at the Serbian capital's Milan Gale Muskatirovic venue.

Lidia Stadniuk of Russia claimed the bronze medal in a time of 36.58.

There was also a tight finish in the men's 100m individual medley race as South Korea's Lee Kwan-ho edged team-mate Kim Taek-yun by 0.01 seconds.

Lee touched the wall in 32.16 to clinch the world title in front of his team-mate, while Tong Zhen Bo of China took bronze in 32.35.

It proved to be a successful day for the Russian team as Maria Patlasova led a one-two from the nation in the women's 200m bi-fin final.

Patlasova stopped the clock at 1min 43.39 sec to defeat compatriot Vitalina Simonova, who was forced to settle for the silver medal.

The bronze medal was sealed by Hungary's Krisztina Varga in 1:44.55.

Russia were denied victory in the men's equivalent as Yevgen Stepanchuk of Ukraine beat Dmitry Kurako to the gold medal after he clocked 1:35.74.

The bronze medal was also claimed by a Russian swimmer as Lev Shtraikh came through to finish third.

The result was reversed in the women's 200m surface final as Ekaterina Mikhailushkina secured the gold medal ahead of Ukraine's Anastasia Antoniak with a time of 1:27.39.

Alina Nalbandian, also of Russia, was the recipient of the bronze medal.

Dmitrii Zhurman completed the success for the Russian side as he won the men's 200m surface final in 1:21.22.

Aliaksandr Biazmen of Belarus and Colombian Juan Ocampo Lozada earned silver and bronze respectively.

The event in Belgrade is due to continue tomorrow.