Aussie swimmers Ariarne Titmus and Mollie O’Callaghan look set for a golden battle in the pool, with both performing strongly in the heats of the women’s 200m freestyle.

O’Callaghan was first in the pool in heat three, and didn’t look troubled throughout.

She was neck-a-neck with her competitors for the majority of the heat, but put on the afterburners to come out on top, gliding to the wall to touch half a length ahead.

Meanwhile, Titmus, who won gold for Australia in the 400m freestyle on day one, took it easy in her heat, looking only to qualify for the semifinals.

She qualified in third, behind O’Callaghan and Canada’s Mary-Sophie Harvey.

On day three, the Aussie duo will race in the semifinals for a spot in the final on day four.