A squad anchored by Australia's fastest woman Torrie Lewis has smashed the national 4x100m record for the second time this year to claim an automatic spot at the Paris Olympics.

Racing at the World Relays meet in the Bahamas, Ebony Lane, Bree Masters, Ella Connolly and Lewis clocked 42.83 seconds to finish second in their heat behind Germany.

It was the fifth fastest overall time, with the top two in each heat advancing to the final and guaranteeing their places for the Olympics in early August.

"I think we all had a lot of trust in each other, so we said, you know what, let's just relax, we've done the work and we've done this a million times," Connolly said.

"Let's just go do this and qualify for the Olympics together."

The same quartet had flagged they were destined for great things by running 42.94 at the Sydney Track Classic in late March, breaking an Australian standard that had stood for 24 years.

Lewis, 19, is also well placed to contest either the individual 100m or 200m in Paris.

The US women were fastest in the Bahamas qualifying round in 42.21.

Australia's 4x100m men went within a whisker of also claiming an automatic Olympic slot on day one at the World Relays.

The young team of Sebastian Sultana, Jacob Despard, Calab Law and Joshua Azzopardi clocked 38.50, only to be pipped for second spot by Jamaica in a photo finish.