Ariarne Titmus set a new 400m freestyle world record, breaking her arch-rival Katie Ledecky's six-year stranglehold.

Titmus came home in 3:56.40 at the Australian swimming championships in Adelaide on Sunday night, just six hundredths of a second faster than the world record Ledecky had set at the Rio Olympics in 2016 when she won in 3:56.46.

The American dominated the discipline until Titmus burst onto the scene last year, winning the 200m and 400m freestyle at the Olympics and claiming silver behind her rival in the 800m freestyle.

The Australian finished in 3:56.69 as she won gold in Tokyo and on Sunday admitted the lack of pressure to perform in a non-Olympic year had helped her going faster.  

'I think the biggest thing since the Olympics was that [...] I have this freedom, the pressure’s off your back,' the 21-year-old told Amazon Prime after setting a new world record.

'I’ve just loved swimming in the past six months and I think going into training with no pressure, just enjoying the sport, it’s underrated how important that is.

'Coming here with no pressure other than the pressure I put on myself - which is still pretty high - it’s fun to come here and swim like that.'

The Tasmanian is the second swimmer to break a world record at the Australian swimming championship after Zac Stubblety-Cook set a new fastest mark in the 200m breaststroke on Thursday night.

Titmus is also the first Australian woman to hold the 400m freestyle world record since Tracey Wickham, whose benchmark remain unbeaten between 1978 and 1987.