The newspaper said the source, who spoke on condition of anonymity, told USA Today that Armstrong's lawyers plan to argue the suit is past the six-year statute of limitations and also that the main issue is not whether Armstrong cheated.
The main issue, the defense team will argue, is whether Armstrong defrauded the U.S. government.
"We will say there was enough information (about doping on the USPS cycling team) to put you (the government) on notice, and you should have filed a false claim before," the Armstrong defense source said.
Armstrong confessed to doping last month after denying it for more than a decade.
The U.S. Justice Department announced Friday that it has joined the civil fraud case against Armstrong for doping under the False Claims Act.