Ronan O'Gara and Marcus Horan also picked up foot and rib problems during a match that despite ending in a five-point haul, has left the Irish camp demoralised.
South Africa put 105 points on the same opposition last month yet Ireland struggled alarmingly in a tournament opener that left head coach Eddie O'Sullivan visibly shaken.
A side containing just five full-time professionals weathered a promising Irish opening to win the second half 14-12 with a rousing performance that brought the Stade Chaban-Delmas to its feet.
With crunch Pool D fixtures against France and Argentina to come, O'Driscoll knows Ireland must overcome the malaise that has set in since the Six Nations.
He said: "Our recent performances are a concern. We know our standings in peoples' minds.
"Everyone knows we can play good rugby, but we've struggled to reproduce the good form we showed in the Six Nations and time is running out.
"We can still top the group by winning the next three games but against Namibia we got what we deserved."
O'Driscoll appeared for the post match press conference with his right arm in a sling, but the Lions skipper insisted it was only a precautionary measure
He said: "I hyper-extended my elbow. The injury will be properly assessed when we get back to the team hotel.
"The discomfort comes and goes a bit. It's a nervy thing. I'm hoping it's not too serious. It's not as bad as it looks."
O'Driscoll, Andrew Trimble and Simon Easterby touched down in the first half and French referee Joel Jutge helped them add two more tries by awarding a penalty try and allowing a controversial late Jerry Flannery score to stand.
Ireland top the group after the first round of matches but their tone after their dire opening effort was one of defeat.
O'Sullivan said: "That was like watching a horror movie - it was our worst performance in a long, long time. We were very, very poor.
"Other than winning the game and getting the bonus point there's no positive we can take from the game.
"I'm struggling to think of an Ireland display during my time as bad as that."