O'Connor – who suffered a torn MCL in the Wallabies' 27-7 loss to the All Blacks at Eden Park before suffering a plantar fascia injury – did not feature on Rennie's team list for the record breaking loss to New Zealand at ANZ Stadium, the upset win against the same opponents at Suncorp Stadium or the frustrating 15-all draw against the Pumas.
But O'Connor started his press conference on Monday by declaring he would be fit and ready to steer the Australians to a season ending win against Argentina at Sydney's Bankwest Stadium on Saturday.
"First things first, I'll be fit this week. I've got to get through selection but we've got there in the end," O'Connor said.
"Being an older player now, you put a lot of work into your body off the field and you just want to do the little things right.
"I came into this campaign and I was given a lot of responsibility and I was very happy with how my game was moving forward and my game was progressing and how we were growing as a team.
"To be cut short and forced to watch from the sidelines, it was very tough."
O'Connor's calming presence was sorely missed in the record breaking loss to the All Blacks in Sydney – when untried debutant Noah Lolesio started at five-eighth – but in the fortnight since, Reece Hodge has done an admirable job at No 10.
In O'Connor's eyes, the Rebels star has done enough to earn a start elsewhere in the backline.
"I think he's definitely earned his spot and [should] stay there [in the starting XV]," O'Connor said.
"I'm not a selector so I won't be pretending where I would put him but I have my ideas and we will see where that plays off. He definitely deserves to be out on the field somewhere.
"In saying that, we still have some really damaging centres that have been doing a really good job for us and the back three as well.
"I'm happy I don't have to make that decision."
The makeup of the Wallabies backline is certainly a conundrum for Rennie.
Hunter Paisami has started to built a powerful pairing with Jordan Petaia in the centres and while the Wallabies started their campaign viewing Hodge as a centre – or a back-up five-eighth – the one position Rennie has not been able to find the right man for is fullback.
Tom Banks hasn't set the world on fire and Hodge's top notch form at No 10 – as well as his reliable strike rate off the kicking tee – could prove valuable against an Argentinian side that seeks to turn every Test into an arm wrestle.
Whether Rennie opts to keep Hodge in his starting XV remains to be seen but O'Connor isn't expecting an enormous overhaul, despite the Tri Nations trophy now being all but out of reach.
"We're taking this game as a must win game for us," he said. "It's very important for our campaign moving forward and for moving forward as a group.
"We've spoken about it a lot. It's not just about finishing the year in this way.
"It's almost about spring-boarding us into this whole campaign.
"It's been a huge year for us with Covid, coming together, new coaches, new group, and I think one thing we haven't spoken about a lot is there has been huge growth – off the field and on the field.
"Now it's just about transferring it and those little margins – ticking the scoreboard over."