Top New Zealand swimmer Lauren Boyle was the stand out performer at the opening session of the national open swimming champs in Auckland, producing the ninth fastest women's 400m freestyle time in the world this year.
Boyle, the 2013 World bronze medallist and Commonwealth champion for the distance, won her heat in 4:06.25 - more than six seconds below the qualifying mark for the world champs in Russia later this year.
Glenn Snyders comfortably headed the qualifiers in the men's 100m breaststroke.
The United States based Snyders cruised to victory in his heat to go within within 0.27 seconds of the World Championships qualification mark.
Another US-based swimmer Matt Hutchins is poised to make a serious bid to secure the World Championships standard in tonight's final of the men's 400m freestyle after topping the qualifiers.
Another swimmer seeking to grab his World Championship opportunity in tonight's final is Aucklander Corey Main who produced an accomplished swim in the heats of men's 100m backstroke to stop the clock in 54.78.
New Zealand's leading Para-Swimmers easily achieved their qualifying standards Nikita Howarth, Sophie Pascoe, Mary Fisher and Rebecca Dubber qualifying for six events for their world championships in July.
Tuesday night's finals session starts at 7pm.