A late try from Jaque Fourie and a last-minute penalty from Morne Steyn secured series victory for the world champions after the Lions had led for most of the match.
O'Gara, who came on as a 68th-minute replacement in Pretoria after injuries saw the Lions use up their full quota of substitutes, was criticised for giving away the penalty that led to Steyn's injury-time heroics having been unable to prevent Fourie from powering over moments earlier.
But now the veteran Ireland fly-half has explained that he was knocked out in a collision with Springbok No8 Pierre Spies prior to Fourie's try and that he remembers little about the incident that saw the hosts take the lead for the very first time at Loftus Versfeld.
"I got knocked out [by Spies] and I tried to get back into the defensive line and missed a tackle. I was aware of Shaun Edwards in my ear going 'are you badly hurt, get back off the ground'," O'Gara told the Irish Times.
"That's exactly what I was trying to do. I wasn't really badly hurt. I was knocked out and didn't really know what I was doing. I can't recall the incident . . . I was knocked out. I just remember trying to throw myself at Fourie and I couldn't see him properly, you know. So I missed him [Fourie]."
And while O'Gara appeared almost inconsolable immediately after the heartbreaking 28-25 loss, the 2001, 2005 and 2009 tourist has now admitted that he believes he made the right decision in hoisting the up-and-under that led directly to Steyn's successful penalty.
The 32-year-old was penalised for making contact with Springbok scrum-half Fourie du Preez in the air and numerous critics have suggested that O'Gara should simply have kicked to touch and settled for a draw rather than attempting to keep the ball alive.
But the Munsterman has defended his decision, stating that the chance of putting the Lions in a position from which to win the match and level the series was one which he would take time and time again.
"Under the posts I kind of had a little time to get myself together," added O'Gara, fresh from a month's rest and recuperation ahead of the new season.
"I remember calling [Tommy Bowe]…to kick that ball, chase that ball and I remember that.
"But that [decision] doesn't cost me a second thought because I'd do the exact same tomorrow. People ask me, 'would you not kick it out' but it never entered my head to kick the ball out. I couldn't see what a draw would do for anyone.
"The way I look at it, you want the win. I kick a contestable Garryowen and maybe we'd retain possession, score the other end of the pitch if we could put ourselves in possession and score a drop goal. That's the way my mind works anyway."