Olympic Champions Stephanie Rice and Libby Trickett have started well during the first heat session at the Olympic Swimming Trials in Adelaide. There is plenty of competition however for spots on the London 2012 Team and both will need to swim quicker on Thursday night.

Rice cast her shoulder problems aside to qualify fourth fastest for Thursday night's 400m individual medley final at the Olympic swimming trials in Adelaide.

Rice clocked four minutes 45.70 seconds in winning her heat on Thursday morning to ensure a berth in the final, where she will need to finish in the top two to seal a spot in the event at the London Olympics.

The 23-year-old faces stiff competition, however, from Blair Evans (4:42.54), Sam Hamill (4:44.11) and Amy Levings (4:44.65), who all qualified quicker than her.

Rice is still in some pain since undergoing arthroscopic surgery in December to repair a torn tendon in her right shoulder.

The reigning Olympic champion brushed the media after her heat swim, saying she would not speak until after the final.

Rice is yet to front the media in Adelaide this week, thought to be a result of her not signing a team agreement with Swimming Australia.

Meanwhile, Libby Trickett produced the best swim of her comeback to qualify fifth fastest for Thursday night's 100m butterfly semi-finals.

Trickett clocked 59.90, breaking the minute barrier for the first time since returning to the sport.

"It's great. To do that in heats is exciting and hopefully with a bit more rest and recovery and freshness I can go faster tonight and tomorrow night," Trickett said.

"I didn't feel nervous before the race .. I was very sort of calm and quiet which was nice. It's my first race at a very major meet for three years."

Jess Schipper (58.35) was fastest qualifier ahead of Marieke Guehrer (59.03) and reigning champion Alicia Coutts (59.21).

Wollongong teenager David McKeon led the way into Thursday night's 400m freestyle final, clocking 3:48.20 to finish fastest ahead of Rob Hurley (3:52.80), Declan Potts (3:53.02) and Ryan Napoleon (3:53.35).

"The first race of the meet, I just wanted to make sure I get through to the final tonight," Napoleon said.

"It's just important not to go too hard especially when tomorrow is the 200m."

Earlier, Travis Nederpelt (4:20.57) touched out favourite Thomas Fraser-Holmes (4:20.73) as fastest qualifier in the men's 400m individual medley final.

Fraser-Holmes conceded he held back over final 100m.

"It was good for a morning swim but not what I wanted, I stuffed up a few things," he said.

"My turns and my break-outs weren't as flash as I wanted, I have just got to be sharper tonight."

The duo were followed by Stephen Parkes (4:22.62) and Daniel Tranter (4:23.05) with teenagers Mitch Larkin and Jayden Hadler also progressing to the final.

Christian Sprenger (1.00.89) swam superbly in his 100m breaststroke heat to be just outside (0.10) the Olympic A qualifier time and well ahead of world record holder Brenton Rickard (1:02.09).

Liam FitzGibbon
AAP