Australian Danni Miatke, former 50m butterfly world champion, has suffered a slipped disc in her back, an injury that could require surgery, casting doubt on her form in Olympic season.

'It just seems to flare up every now and then. But we're trying to manage it,' coach Rohan Taylor told the Northern Territory News.

Miatke, 20, raced at the Victorian championships in Melbourne this week but was well below par, finishing 33rd over 100m and 4th over the non-Olympic 50m in 27.44sec, compared to a best of 26.05.

Carey Aquatic coach Carl Wilson said: 'I'd like to say she is going to be right [in time for Australia's Olympic trials] but it is a back injury and they are quite delicate. Some days they are good and some days they go back. So it is bit in limbo at the moment. I'd say she is not too bad off if she can compete for the last five days at state. But naturally her times have been down because she hasn't been in the water as much.'

Miatke was world champion over 50m butterfly at Montreal in 2005. She won the Commonwealth crown a year later.