And O'Driscoll, who had his knee strapped all through the 2011 RBS 6 Nations, foresees an anxious week ahead as Leinster prepare for their Northampton Saints showdown.
"It's a bit in the balance for the weekend," said O'Driscoll.
"I'm not training today and don't envisage doing much tomorrow.
"I have a chance later in the week to prove my fitness and I'll just have to take it day by day.
"It feels a bit better from Friday night, so I have to see if it steps up another level.
"I've had my knee strapped through the Six Nations and November, I've had it strapped for almost 18 months.
"Looking back at the video footage, I got my leg caught in the wrong position and couldn't get it out of there.
"You can't go stressing too much, what's going to be is going to be, you have to deal with it.
"I barely stepped outside the house at the weekend.
"I had the ice machine on for the swelling to put myself in a position to recover as best as possible."
However there was better news for Leinster coach Joe Schmidt with hooker Richardt Strauss, scrum-half Isaac Boss and the region's most capped Heineken Cup player Shane Horgan all expected to recover in time for the Millennium Stadium match-up.
Northampton look set to be without Tom Wood in Cardiff as the England flanker is unlikely to recover from a hairline leg fracture in time.