Horn, who finished eighth at last year's Olympics, was in good form in challenging windy conditions at the famous Troja venue in Prague as she booked her place in Sunday's (June 18) final. 

She finished in 87.65 seconds, 1.61 quicker than Slovakia's Jana Dukatova and 2.61 in front of the Czech Republic's world champion Katerina Kudejova.

Spain’s Olympic champion Maialen Chourraut finished 7.98 behind Horn, New Zealand’s silver medallist Luuka Jones trailed by 3.83 and Australia's Jessica Fox was 5.06 behind.

"I was paddling without being nervous because I really like the course," Horn said.

"But I thought I was in delay, because I was listening to the speaker and obviously it was not quite what I was hearing."

In the men's K1, it was Australian Lucien Delfour who upstaged the Rio 2016 medallists, posting a time of 77.73 to head qualification. 

Britain’s Olympic champion Joseph Clarke finished 11th today, 2.73 behind Delfour.

Slovenia’s Peter Kauzer, the silver medallist in Rio, was 1.60 off the lead while bronze medallist Jiří Prskavec of the Czech Republic was 0.84 behind.

In the men’s C1 it was Slovakia’s Alexander Slafkovsky who headed a surprise top three, finishing in 84.88 in front of Spain’s Ander Elosegi in 86.02, and the United States’ Casey Eichfeld in 86.41.

"I like Prague, I like to race here," Slafkovsky said.

"My goal was to finish top 20, so it’s worked very well.

"But on Sunday it's a new race, new course, so it doesn't mean anything today."

Possibly the most impressive performance today came from Austria’s Nadine Weratschnig in the women’s C1.

She posted a speedy 94.88 to finish 4.55 in front of Britain's Mallory Franklin, with fellow British paddler Kimberley Woods third.

In the men's C2 the Czech pair of Jonas Kaspar and Marek Sindler were the quickest, with their time of 93.92 well ahead of Slovakia's Tomas Kucera and Jakub Vrzan in 96.41.

Action in Prague is set to continue tomorrow with the finals of the men's C2, the women's C1 and the men's K1 disciplines.