David Humphreys (left) is likely to have a key role in Perth

A failed drugs test by hooker Frank Sheahan and injuries to several players has failed to diminish Irish confidence for Saturday's Test against Australia in Perth.

Ulster's Paddy Wallace is Ireland's latest injury worry and will be unavailable for the game in Perth because of a foot injury but should be available for the Tonga and Samoa Tests.

"We've won 10 of our previous 11 matches and only been beaten once, by England," team spokesman John Redmond said on Monday.

"Our 10 matches include a victory over Australia last November so we're in pretty good shape," added Redmond.

Irish hooker Sheahan arrived with coach Eddie O'Sullivan's depleted squad last week before flying out again on Saturday after learning he had failed a drugs test.

Sheahan tested positive for salbutamol after the European Cup semi-final between Munster and Toulouse in April.

He is automatically suspended from playing until European Rugby Cup, the competition's organisers, have completed their procedures.

However, Sheahan said the positive finding stemmed from his failing to fill in the right part of a form which declared the use of the substance as an anti-asthma treatment.

We are not dwelling on who we don't have IRFU spokesman John Redmond

Redmond said: "Frank went back to Dublin on Saturday. All the indications are that it's been an administrative error".

Ireland captain Brian O'Driscoll and former skipper Keith Wood will both miss Saturday's match because of injuries.

Wood, however, is training with the squad as part of the inspirational hooker's bid to play in the World Cup in Australia later this year.

Winger Denis Hickie last week joined Ireland's injury list alongside Shane Horgan, John Hayes, Jeremy Staunton, Neil Doak, number eight Anthony Foley and centre Rob Henderson.

Australia and Ireland are both expected to name their teams on Tuesday.

"These injuries, every country has them. That's why we must get on with it. We are not dwelling on who we don't have," Redmond said.

"The objective is the same, the objective is to win the match so we're confident we're going to be able to do that".

Ulster fly-half David Humphreys is expected to be named Irish skipper for Saturday's Perth contest.

Ireland's tour includes matches against Tonga and Samoa.

Australia's first Test of the year on Saturday will be followed by matches against Wales and England later this month.