Kiddle was fastest in a field which included Sweden’s Emma Fredh, the reigning European champion, on Lake Malta in Poznan.

Local favourite Joanna Dorociak of Poland stormed out of the blocks with Fredh following in second and Switzerland's Patricia Merz in third.

Merz won gold at the first World Rowing Cup of the season in Belgrade and bronze at the European Championships in Račice in the Czech Republic.

At the half-way mark, Dorociak was still in the lead, Fredh still in second and Merz in third with Denise Walsh of Ireland, this year’s European silver medallist, surprisingly at the very back of the field.

With just a quarter of the race left, Kiddle moved up from her initial sixth position into fourth.

In the final strokes, four scullers were all within half a length of each other but Kiddle upped her pace and managed to sneak across the line first in a photo finish with Dorociak in silver and Merz, one hundredth of a second further back in third.

"I am really stoked about that race," said Kiddle.

"I was quite worried to be down at 500 metres, but I believed in the training and my fitness and that helped pull me through.

"In the last 500m, I just said 'drop the clutch' and I went."

Austria's Anja Manoutschehri won the B final.

In today's semi-finals Victoria Thornley of Britain progressed to tomorrow's final in the women's single sculls event.

The European champion narrowly beat Germany's Annekatrin Thiele with Ukrainian Diana Dymchenko taking third.

In the other semi-final, China's Duan Jingli prevailed.

The Rio 2016 bronze medallist beat Austria's Magdalena Lobnig and New Zealand's Hannah Osborne, who placed second and third respectively.

Croatia's Rio 2016 and London 2012 silver medallist Damir Martin was beaten in his men's single sculls semi-final but still advanced to tomorrow's final.

Robert Manson of New Zealand and Martin moved clear of the rest of the field in the early stages and cruised to the top two.

Late charges came from Serbia's Marko Marjanovic and Belarus’ Stanislau Shcharbachenia but Britain's Thomas Barras clinched third place.

They will be joined in the final by Cuba’s Angel Fournier Rodriguez, who was an Olympic finalist last year, placing sixth.

Germany’s Tim Ole Naske, the reigning under-23 champion, also progressed with Nico Stahlberg of Switzerland.

Rio 2016 bronze medallists Kjetil Borsch and Olaf Tufte of Norway reached the final of the men's doubles sculls.

Australians Luke Letcher and David Watts won their respective semi-final with the Bulgarian duo of Georgi Bozhilov and Kristian Vasilev also making it through to tomorrow's final.

Action in Poznan will conclude tomorrow.