The seven-time Tour de France winner curtly brushed aside questions about the story before taking part in Wednesday's second stage of the Tour Down Under.
In a report posted Tuesday on its website, Sports Illustrated magazine previewed a longer investigative piece that will appear in this week's issue, available Wednesday, that challenges Armstrong's statements that he cut ties to an Italian doctor and training adviser who has long been accused of helping cyclists cheat.
Armstrong repeatedly refused to comment on the report Wednesday before saying he had perused it and "I have nothing to worry about on any level." Johan Bruyneel, Armstrong's mentor and the manager of this Radio Shack team, also refused to discuss the report.
Without identifying its source, Sports Illustrated said that when Italian authorities raided the home of Armstrong teammate Yaroslav Popovych last November in Italy, they found texts and e-mails linking the Radio Shack team with Dr. Michele Ferrari as recently as 2009.
Armstrong publicly severed his connection with Ferrari in 2004, amid accusations the doctor aided another rider in using performance-enhancing drugs. Ferrari was convicted and then later cleared of criminal charges on appeal.
Armstrong spokesman Mark Fabiani called the Sports Illustrated report "old news from the same old, discredited sources."
A U.S. federal grand jury in Los Angeles has been hearing evidence for months on cheating in professional cycling. The investigation turned toward Armstrong - and several of his associates have testified before the panel - since ex-teammate Floyd Landis accused the seven-time Tour de France winner of systematic doping.
Armstrong won the Tour de France every year from 1999 to 2005. He is currently 60th overall after two stages at the Tour Down Under, which Armstrong has said will be his final race outside the United States.