Three new caps, seven changes in personnel and one positional switch since the last day, as well as a couple of vacancies in the back row made for a relatively radical Irish selection in Brisbane yesterday. The bottom line though, bearing in mind the evidence of two contrasting tour games, is that it's very much a form selection.

The composure and slickness of 22-year-old Tom Tierney has earned the Garryowen player the scrum-half slot ahead of Ciaran Scally, Brian O'Driscoll's knee injury was always going to raise doubts about his selection despite the undoubted class he has brought to the Irish midfield, while Matt Mostyn's strength and finishing outweighed the misfortune of Girvan Dempsey in seeing his opposite winger score four tries last Saturday.

Although there are another four changes in personnel from the team which accounted for Italy last time out, a more relevant barometer is the Irish XV which started against Scotland in the last Five Nations match. Compared to that day, there is only one other change, and that is in the back row due to the absence of the injured Eric Miller.

The make-up of the back row, where that most capped player of all, AN Other, makes a double reappearance, has still to be resolved pending fitness updates on Victor Costello, David Corkery and Trevor Brennan. One of that trio will partner Andy Ward and Dion O'Cuinneagain, with the latter to play on the blind side if Costello is picked, or alternatively at number eight if Corkery or Brennan are selected.

Brennan, on the basis of his fairly solid display against New South Wales, is arguably the favourite, all the more so as O'Cuinneagain's presence in more of a decision-making position at number eight might alleviate some of the strain on the debutant Tierney.

Regarding the state of Brennan's strained shoulder ligaments, Lenihan said: "Well, he won't take contact today. . . Ideally, we'd like him to train tomorrow. David Corkery and Victor Costello had their first real contact training in a week today so, ideally, we'd like to have the back row sorted out by tomorrow's session."

Asked which was the selection which provoked the most discussion amongst the management, Donal Lenihan volunteered: "The scrum-half area was obviously one that took a fair bit of discussion. We were very happy with Tom Tierney the other night (against New South Wales Country). Scals (Scally) did a lot of good things on Saturday, but I think overall Tom Tierney's service has been that bit sharper. He hasn't played at this level - Scally has - and we said one of the reasons for coming out here was to have a look at the newer players, so he gets his chance on Saturday."

The other big loser is undoubtedly Dempsey, for this is effectively the first time since he broke into the team that he has not been selected if fit. Indeed, it's hard not to feel a little sympathy for him as Matt Dowling's four tries were far more the product of a passive Irish midfield defence than any lack of aggression on Dempsey's part.

It wasn't as if Dempsey missed any glaring tackles, and the irony is that this week's defensive refresher course and the greater speed of next Saturday's Humphreys-Maggs-O'Driscoll midfield axis in pushing up the line is likely to leave the wingers far less exposed.

Lenihan admitted it was a hard call, but added: "We've been impressed with Matt Mostyn in the two games and we want to see him at international level."

Excited about some of their new attacking combinations, not least O'Driscoll, who has been the embryonic success of the tour so far, Lenihan said: "To be fair to him he's up against a very experienced centre combination in Herbert and Horan, so you've got to take that into context for a young fella as well but I think he is the type of player we've been looking for."

Meanwhile, Lenihan conceded that "the defensive areas have certainly occupied our minds. We studied the video at length. We sat down with the backs and forwards separately and together, and I think we've identified the problems and hopefully we won't see a repeat of them again on Saturday."

Another area of concern would undoubtedly have been the numbers getting to rucks, especially from the tight five. Here though options are limited, and it could be that only Peter Clohessy and Keith Wood will be added to the pack which started in the defeat to New South Wales.

Ireland (v Australia): C O'Shea; J Bishop, B O'Driscoll, K Maggs, M Mostyn; D Humprheys, T Tierney; P Clohessy, K Wood, P Wallace, P Johns, J Davidson, AN Other, AN Other, A Ward. Replacements: C Scally, E Elwood, J Bell, AN Other, M O'Kelly, R Corrigan, R Nesdale.