The Republic must overturn a 1-0 first-leg deficit on Wednesday night if they are to book their place in next summer's finals in South Africa.
Giovanni Trapattoni's side lost to a deflected Nicolas Anelka goal at Croke Park in Saturday's first leg, but Spurs striker Keane is hoping for a reversal in fortunes in Paris.
"As a team, we know exactly what we have to do," he declared. "We have to go out and perform and make sure we have got no regrets.
"Overall, in the campaign itself, we haven't lost away from home and that has given us a lot of confidence.
"The manager has instilled that into us because the performances away from home have certainly been good and that's something we can take in.
"It has been a decent campaign for us but it will mean nothing if we don't produce.
"We are in this campaign to be at the World Cup and this will decide it."
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