But Lions skipper O'Connell says his team should never have been in a position to lose the game and that O'Gara is mentally tough enough to hit back this weekend
"Ronan is disappointed and very low. But he's a tough guy mentally - that's his biggest strength," said O'Connell.
"What happened in the second Test won't be lost on him, but the tough guys bounce back and Ronan is one of them. When you keep putting yourself out there for selection in the big games these things happen.
"Our careers aren't always up, up, up. We should have been away and the game should have been over by that stage and we all have bad days.
"Ronan has had many brilliant days, where he has won games single-handedly, and I'm lucky enough to have won a few medals because of his brilliance. I don't think I would have any of them if it wasn't for him.
"He's extremely disappointed and, no doubt, he will beat himself up over it, but he will bounce back."