D-Day has arrived for Ian Thorpe. One of the most anticipated comebacks in Australian sport will be judged when Thorpe contests Friday's 200m freestyle heats at the Olympic trials in Adelaide.

The five-time Olympic gold medallist will be hoping to reach Friday night's semi-finals and from there a spot in Saturday night's eight-man final.

Then he will need a top two finish to book an individual berth at the London Games or top six to be considered as a relay swimmer.

Check out the times Thorpe has been swimming compared to the A and B qualifying times here.

Standing in Thorpe's way is a field of promising swimmers, not least 20-year-old favourite Thomas Fraser-Holmes who ominously produced one of the swims of the opening night on Thursday.

Fraser-Holmes smashed the Australian record in winning the men's 400m individual medley.

Earlier on Thursday he said he would not be daunted by Thorpe's presence in the 200m.

"What he's done is incredible," Fraser-Holmes said.

"But, no offence, that was a couple of years ago.

Libby Trickett will be looking to get the jump on Thorpe's comeback bid in Friday night's final of the 100m butterfly.

Trickett produced the two best swims of her comeback to qualify sixth fastest for the final, with Jess Schipper topping the heats ahead of favourite Alicia Coutts.

Brenton Rickard was fastest qualifier into the 100m breaststroke final ahead of arch rival Christian Sprenger.

They will be hoping to join Stephanie Rice on the team, after the triple Beijing Olympic champion took out the women's 400m individual medley in a world class time of 4:33.45 on Thursday night.

Despite a tainted build-up due to her troublesome shoulder, a wiser Rice believes she can keep improving in her bid to defend her title in London.

"I'm older now, I'm a different athlete, I think I'm a lot more confident now than I was when I was 18 and obviously it has been a really tough mental preparation as well to get my head around surgeries and inconsistent training," she said.

"To come away now with a really solid swim and a world class time ... I'm really excited."

Teenager David McKeon caused an upset in taking out the men's 400m freestyle title.

The Wollongong swimmer finished over the top of Ryan Napoleon, who also clinched an Olympic berth.

Both are in Thorpe's 200m freestyle heats on Friday morning.

Also on Friday Kylie Palmer and Bronte Barratt go head-to-head in the 400m freestyle.

Liam FitzGibbon
AAP