NEW YORK -- Lance Armstrong says he has nothing to worry about "on any level" over new doping allegations raised in a report by Sports Illustrated.

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.

A story in Sports Illustrated challenges Armstrong's statements that he cut ties to a controversial Italian doctor and training adviser who has long been accused of helping cyclists cheat.

In a report posted Tuesday on its website, the magazine previewed a longer investigative piece that will appear in this week's issue, available Wednesday.