A Niall Ronan try and four penalties from Ronan O'Gara, on his 100th appearance in the competition, lifted the Irish side to a 17-14 victory, with O'Connell's efforts earning him the man of the match award.
But despite his personal accolade, and his side's continued march on the European stage, O'Connell has warned against getting carried away as he prepares to welcome Scarlets to Thomond Park next Sunday.
"It's a hell of a win for us and we are absolutely thrilled with it, but we are fully aware it's only half-time," O'Connell said.
"From our point of view there is nothing like a loss to focus the mind so I'd imagine next week will be an incredibly tough game.
"It's a great win and we are very proud of it. I thought our pack was excellent. We got a lot of yardage from our scrum and some points from our scrum.
"It's massively important we have got a home game next but it's not like we are running away with any games. Every game is a fight to the death at the moment and every game is a battle.
"There is no danger of us getting ahead of ourselves. We know how close the games are and we will be fully focused against the Scarlets next week."
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