World championship and Olympic bronze medallist Julia Greville has become the third Australian swimmer, forced out of next month's Qantas Pan Pacific Championships in Sydney with a shoulder injury.

The news of Greville's withdrawl follows the US loss of Dianna Munz, following a car accident and Tom Dolan, who has failed to recover from knee surgery, following a bacsketball accident.

Greville was due to enter hospital today in Perth for an operation to remove a cyst from her troublesome right shoulder.

She informed Australian Swimming yesterday of the decision, after succumbing to weeks of training in pain.

The 1998 World Championships bronze medallist in the 200m freestyle now joins Olympic silver medallists Petria Thomas and Daniel Kowalski on the sideline after they too underwent shoulder surgery in recent months.

It is the final straw for Greville who has had a wretched year of bad luck. Just two weeks before this year's Telstra Australian Open Championships, Greville suffered bruised ribs in a car accident and then in May she was in hospital in Melbourne with a kidney infection.

Her coach in Perth, Bernie Mulroy said today: "Let's hope Julia comes through this operation and gets all the bad luck out of the way."

"She's certainly had no luck at all this year." Greville has been in pain in recent weeks, even when she was reduced to kicking.

It severely hampers Australia's depth - particularly in the 200 metres freestyle. Both Thomas and Greville were members of the bronze medal winning 4 x 200 metres freestyle relay at last year's World Championships in Perth.

Commonwealth record holder Susie O'Neill will be the only survivor of that team after Anna Windsor failed to qualify for this team.

Head coach Don Talbot will rely even more heavily on the talents of youngsters Lori Munz, Giaan Rooney and Rebecca Creedy to fill the void.