Ireland coach Eddie O'Sullivan has made one change to the side for Saturday's clash with Australia (Subiaco Oval, Perth, 11.00am), bringing in Girvan Dempsey for Geordan Murphy at full-back.
Murphy drops to the replacements bench, where there is one other change from the matchday 22 for the second Test against New Zealand - London Wasps out-half Jeremy Staunton gets the nod ahead of Denis Hickie.
It will be Dempsey's first start in an Irish jersey since the second Test victory over Japan in Tokyo twelve months ago.
Saturday will see flanker David Wallace earn his 30th cap, his Munster colleague Marcus Horan will gain his 40th at loosehead prop. Another of the Munster contingent, scrum half Peter Stringer will also equal the old caps record of legendary centre Mike Gibson (69) at the weekend.
Discussing his team selection at Tuesday's press conference, O'Sullivan said: "I don't think Geordan is on top of his game at the moment, and I think he would be the first to admit that. I said at the start of the tour I would would try and pick the best team each week."
Asked about Australia's form during their recent Cook Cup series against England, he added: "I don't know what the average score was in the first two Tests, but they look like they have hit the ground running. Their back line is firing, they're playing some very accurate rugby and running some great lines. An aspect of rugby I've always admired is Wallaby back play, and I've tried to follow that myself to a fair degree.
"I think they have taken a fair bit of pressure off the Wallaby pack, and given them a chance to get their game together."
Australia and Ireland will be meeting for the 25th time in a Test match this weekend - the Wallabies lead the way with 17 wins.
IRELAND TEAM AND REPLACEMENTS (v Australia, Subiaco Oval, Perth, kick-off 11.00am Irish time, Saturday, June 24):
15 - Girvan Dempsey (Terenure College/Leinster) 65 caps
14 - Shane Horgan (Lansdowne/Leinster) 47
13 - Brian O'Driscoll (Blackrock College/Leinster) (captain) 66
12 - Gordon D'Arcy (Lansdowne/Leinster) 22
11 - Andrew Trimble (Ballymena/Ulster) 8
10 - Ronan O'Gara (Cork Constitution/Munster) 62
9 - Peter Stringer (Shannon/Munster) 68
1 - Marcus Horan (Shannon/Munster) 39
2 - Jerry Flannery (Shannon/Munster) 8
3 - John Hayes (Bruff/Munster) 64
4 - Donncha O'Callaghan (Cork Constitution/Munster) 26
5 - Paul O'Connell (Young Munster/Munster) 35
6 - Neil Best (Belfast Harlequins/Ulster) 4
7 - David Wallace (Garryowen/Munster) 29
8 - Denis Leamy (Cork Constitution/Munster) 13
16 - Rory Best (Belfast Harlequins/Ulster) 3
17 - Bryan Young (Ballymena/Ulster) 1
18 - Mick O'Driscoll (Cork Constitution/Munster) 6
19 - Keith Gleeson (St. Mary's College/Leinster) 24
20 - Isaac Boss (Ballymena/Ulster) 1
21 - Jeremy Staunton (London Wasps) 3
22 - Geordan Murphy (Leicester Tigers) 41
Referee: Kelvin Deaker (New Zealand)
Touch Judges: Steve Walsh, Bryce Lawrence (New Zealand)