Five-time Olympic medalist and four-time world track champion Marion Jones says she is shocked by her positive doping test for the synthetic hormone EPO.

The American star's positive test came June 23 at the U.S. Outdoor Track and Field Championships, where she won the 100-meter sprint. The victory was her 14th national title but first since 2002.

Jones said Monday that she wants the second, or so-called B-sample examined quickly. Jones could face a two-year ban if her second sample is also positive. She has vigorously denied ever using performance enhancing drugs.

Dick Pound, the chairman of the World Anti-Doping Association, says the U.S. Anti-Doping Agency has closely watched Jones because of her ties to the scandal-plagued Bay Area Laboratory Co-Operative.

Some information for this report was provided by AFP and AP.