Madigan notched 13 points from the kicking tee in the victory and with Sexton nursing an injured thumb the chance is there for a new Ireland No.10 against Italy this weekend.
Ulster's Paddy Jackson is probably the front runner to replace Sexton but O'Connor is confident Madigan is the man for the job.
"Mads' performance was very, very good," he said.
"His goal-kicking was exceptional. In really tough conditions, he kept us in the game and was ultimately a significant part in us getting the result.
"It's not my call but of course he is [ready]. He's playing really well. He managed tough conditions and field position and, like I said, he's a world-class goal-kicker.
"If Joe (Schmidt) goes down that road and decides to give him that opportunity, I'm sure he'll do a great job."
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