Four years after his last test, and 12 since he last faced the Lions, the 32-year-old openside flanker was named in the Wallabies starting line-up for the third test against the tourists at Sydney's Olympic stadium.
Smith said his 111th test would definitely be his last and hoped his unexpected swan-song on Saturday concludes with a 2-1 series win over the Lions to match the one he helped orchestrate in 2001.
"In terms of rugby, it's the ultimate for me," said Smith. "To be selected in the starting 15 for this decider, there's nothing higher for me at the moment.
"To have longevity to play consecutive series in Australia, I'm very pleased.
"It's something that when it's all done I'll reflect on the magnitude of but at the moment it all about focusing on the job at hand and that's winning this Saturday."
Smith's return to the Wallabies fold is all the more remarkable given he badly injured his knee playing Super Rugby on the eve of the initial squad announcement in late May.
It was testament to his work ethic that he managed to confound the doctors and put himself in a position to be considered by coach Robbie Deans for selection, and even then he was by no means sure he would play.
"I didn't think, I was hoping," he said. "The recovery I've had since the injury against the Waratahs has been fantastic. Those four weeks leading up to being invited into the camp last week were very intense.
"I was probably very selfish with a lot of the things I did, I didn't do too much media, didn't spend as much time with the family as I should have, because I wanted to be a part of this series."
Smith said it was difficult to compare this week's match to the final test of the 2001 series, when he was a dreadlocked 20-year-old unaware of the magnitude of what he was involved in.
He is sure, however, that he is a more complete player now.
"I've changed enormously," he said. "I played on instinct in 2001, I'd only had three or four test matches under my belt. So I was very green in terms of my game play in terms of being in the right spot at the right time.
"My rugby awareness is a lot better nowadays, my understanding of rugby players and why we do what we do, why you run these lines, why you tackle a certain way.
"I've played a lot of rugby and if you pick up one thing each time you play, there's a wealth of knowledge there.
"I'm not saying I'm a perfect player or anything like that, I'm just a student of the sport."
Smith said that like many Australians, he had anxiously paced around his house at the conclusion of the first test defeat in Brisbane when Kurtley Beale missed what would have been a match-winning penalty.
His first thought after the second test victory in Melbourne was delight for the Australia players, he said, and he was expecting another close contest in the decider on Saturday.
"I think they've played some really good rugby," he said of the tourists, who will be without injured captain Sam Warburton for the series decider.
"They've got some big, strong running centres who we're going to play this week. They're very good at the breakdown as you saw last week.
"Obviously Warburton's not there this week but Sean O'Brien's a very good player. So I'm looking forward to a realy good contest, a real robust game.
"Hopefully not too many penalties and plenty of running rugby."
Michael Hooper, who started the first two tests in the number seven shirt, said he had few complaints about being bumped down to the bench to make way for Smith.
"He came in last week and immediately brought a great presence. It's very special that it's my first time playing with him. Everyone wants to play in that starting jersey but if the 110-cap veteran gets it then ..." he shrugged.