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Boyle, who won the 800m freestyle and was third in the 400m freestyle, produced a superb swim to be fourth fastest in the heats today. The 24-year-old from the North Shore club clocked 1:55.40, just over a second under the previous record set by backstroke specialist Melissa Ingram in 1:56.32 at the 2008 World Cup meet in South Africa.
Boyle said she would treat the morning heat like a final as her best chance of qualifying, with only 0.8 seconds separating the top eight qualifiers.
Ingram, 27, was 15th fastest in 1:57.38, producing her best time of the year to complete a strong championship for the veteran North Shore swimmer, coached by Scott Talbot.
Earlier Howick Pakuranga's Corey Main was 17th fastest in heats of the men's 200m backstroke in 1:54.70, to be a fraction outside his best with the top eight through to the evening finals.
Boyle will be the only New Zealander on the evening programme while fellow Swimming New Zealand High Performance Centre swimmer Matthew Stanley has his timed final in the 1500m freestyle at the end of the morning session, with the fastest heat to be swum at night.