SWIMMING: Olympic great Grant Hackett's quest for a comeback is going from strength to strength.

In a stunning return to the pool, he is swimming as fast as Ian Thorpe did three years ago after less than half the time back in full training.

Just six months into his comeback, Hackett has already posted multiple 200m freestyle time trials in training of one minute 50 seconds, only a touch off Thorpe's 1:49.91 effort when 12th at the 2012 Olympic trials in Adelaide.

Hackett made an encouraging start in his bid to qualify for Australia's swimming squad for the Rio Games.

He swam in three events at a qualifying meet at the Brisbane Aquatic Centre in his first competitive outing since the 2008 Olympics in Beijing.

The triple Olympic gold medallist won with an impressive time in the 400 metres freestyle, and backed up with second-place finishes in the 200 metres and 100 metres.

Hackett will return to action on the Gold Coast next week before heading to the National Championships in Sydney in April.

His 400m and 200m times are expected to be ratified as world records in the Masters 30-34 age group previously held by Daniel Kowalski.

He told News Corp Australia he had doing a time of around 1:50 since December.

"I never thought I'd get to that time at this sort of stage, particularly in full training," Hackett said.

He said a time of 1:48 or even 1:47 remained his goal.

"Perhaps if I was tapered and shaved at trials coming up, that (1:48) might be something realistic.

"You could get to 1:48 but getting to 1:47 could take another 12 months.

"It might be a shorter time frame for me because I've done it so much over my life.

"I'm always conscious of not creating too much expectation on myself. Not really from public point of view, it's more myself - there could be a stage where my body says you can't push to the next level," said Hackett.

AAP