Olympic and world champion Zhao Shuai triumphed in the men's under-68 kilograms category and Zhou Lijun came out on top in the women's under-57kg division at the Exhibition Forum Events Center of the Bulgarian capital's Hotel Marinela.

Both saw off South Korean opposition in their finals, with Zhao beating three-time world champion Lee Dae-hoon 17-7 and Zhou defeating Lee Ah-reum 15-12 to secure her first-ever Grand Prix title.

Iran's Soroush Ahmadi and Chinese Taipei's Huang Yu-jen were the men's under-68kg bronze medallists.

Rounding off the women's under-57kg podium were Russia's Tatiana Kudashova and Turkey's Hatice Kübra İlgün.

Despite missing out on gold medals in the first two finals, South Korea were guaranteed one in the men's under-58kg category after both Jang Jun and Kim Tae-hun reached the title contest.

It was Jang who prevailed, taking a 12-1 victory.

The bronze medals went to Iran's Armin Hadipour Seighalani and Italy's Vito Dell’Aquila.

Today’s action was preceded by an opening ceremony, during which speeches were delivered and awards presented by World Taekwondo President Chungwon Choue, Bulgarian Taekwondo Federation counterpart Slavi Binev and Bulgaria's Minister of Youth and Sports Krasen Kralev.

The ceremony also saw the World Taekwondo demonstration team perform.