O'Sullivan told a news conference O'Driscoll had come through training sessions on Tuesday and Wednesday without any trouble.
"All the indicators are now he'll be fine," O'Sullivan said.
Speaking of D'Arcy he added: "It's just going to take more time than we thought."
O'Driscoll and D'Arcy both missed the second round 40-13 win over Scotland.
Kevin Maggs has been relegated to the bench in the only change from the Scotland match.
RSS