Australian star Tim Cahill is no certainty to start in the Uzbekistan clash in Sydney tonight.

Cahill hurt his calf less than two weeks ago playing for Everton and has not been 100 per cent since.

Coach Pim Verbeek is unsure how he will use Cahill at this stage.

"The situation with Cahill is the same. Of course, we'd like to have Timmy on the field - he is one of our key players," he said.

"From the start we knew that he would be 100 per cent fit or maybe not.

"It's all about are they ready to play 90 minutes?"