A try from impressive full-back Keith Earls and two successful place-kicks from O'Gara got the tourists off on the right foot, but the Emerging Springboks, coached by South Africa assistant coach Dick Muir, produced a determined second half comeback.
Earl Rose kicked them back to within a point at 10-9 and although O'Gara's replacement James Hook got it back to four with a 77th minute penalty, Danwel Demas ensured a dramatic finish when he touched down in the right corner in the last minute.
The Emerging Springboks needed Willem de Waal to land the conversion from close to the right touchline to secure a famous draw with Ian McGeechan's side and despite an untimely downpour, he did just that by splitting the posts from a very difficult position.
No doubt O'Gara will have congratulated de Waal on his coolly-struck kick afterwards, but there were conflicting emotions for the Corkman afterwards.
He was replaced after 45 minutes by the Lions management. That could either mean that he will be playing some part or more in Saturday's second Test, or that the fit-again James Hook was just being given a chance to make his own case for inclusion in the Test 22.
Keeping an open mind about it, O'Gara said: "The plan was to play for 40 minutes and try to stake a claim for the weekend. It was a big game in itself so as much game-time was appreciated.
"If you miss out (on selection), the initial disappointment is huge but the most important part now is the team. When you come in, you've got to make an impact.
"We're 1-0 down (in the series) but there's still a great belief amongst the boys. We will wake up angry again tomorrow and that is what we will need for the weekend."
When O'Gara was replaced by Hook, he felt that the Lions were capable enough of building on their 10-3 half-time lead and putting the Emerging 'Boks under increased pressure - but the hosts had a very different idea.
"The way it ended, it probably feels like a defeat to be honest. It seemed we were very much in control of that game.
"It's probably difficult for me when you leave the pitch after 45 minutes - I felt things were sweet.
"But we never really pulled away from them, they came back and got the late try and conversion, so credit to them."
The driving rain and testing wind made maintaining possession particularly difficult and produced a number of knock-ons and turnovers, doing little for the flow of the game.
"We would much have preferred a dry day and ball, especially as both midweek teams were trying to express themselves," said O'Gara, who was the fifth different player to captain the 2009 Lions.
"There was a good crowd, two competitive teams, but the conditions were very difficult.
"There was a swirling, gale force wind. It was really strong, all over the place, underfoot conditions were very difficult.
"It was hard, you saw the amount of turnovers and errors that were made on both sides.
"Skill levels will have to be improved but I think conditions played a big part in that too."