Joe Schmidt's charges are under pressure to restore the faith after losing their last four Tests of 2025.
Schmidt has turned to Campbell after a 1316-day exile from international rugby to be the voice and calming influence against the third-ranked Irish in Saturday night's Nations Championship opener in Sydney.
"I'm so happy for Jock. He's worked so hard to get back here. His Super Rugby performances were unbelievable," skipper Harry Wilson said of his Queensland Reds teammate.
"He's come back this year fitter, faster and stronger than I've ever seen him at 31 years old, and that's a credit to him about how hard he's worked."
But Wilson noted that Campbell brings much more than flair in attack.
"He's quite a loud talker at the back,'' Wilson said.
"He's a very calm person. He knows his role and he's really good at helping the people around him too.
"He'll be really good for the other two in the back three - Jorgo (Max Jorgensen) and Peachy (Dylan Pietsch) - because his chat is unbelievable and nothing really flusters him."
Another Reds star will be playing his first Test on home soil in three years, with flyhalf Carter Gordon winning the No.10 jumper following a stint with NRL's Gold Coast Titans, before returning to the Wallabies fold on the 2025 spring tour.
"It's been really good for Carter to have a pretty injury-free year for the Reds," Wilson said.
"So he got a lot of footy for us and he loves the defence side of being a flyhalf. He's always wanted to get in there.
"His chat, his communication was really good for us at Reds, and since he's come to Wallaby camp he's really grabbed that and he's been leading that.
"He's had a really good two weeks in the hot seat."
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