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The team of Shayna Jack, Bronte Campbell, Emma McKeon and Cate Campbell lowered the previous world record of 3:30.65 set by Australia at the 2016 Rio Olympics.
Cate Campbell brought home the world record with a flying final leg of 51.00secs after sister Bronte was under world record pace with her second leg of 52.03secs.
Australia beat out Canada and England for their second swimming gold of the opening night after Olympic champion Mack Horton won the 400m freestyle final earlier in the programme.