LEXINGTON, Ohio (AP) - Anthony Gobert, a leader in one of the nation’s top motorcycle racing series, has been suspended from competition for the rest of the year after testing positive for marijuana.

The suspension was announced Friday by the American Motorcyclist Association after the organization received results of a urine sample taken earlier in the day.

The positive test was his second this month and third since last fall.

Gobert, 22, of Australia, was banned indefinitely from racing at the world level last fall after testing positive at an event in the Czech Republic. A similar test result this month made him ineligible for an AMA event at Laguna Seca, Calif.

In addition, he admitted smoking marijuana June 21 following a third-place finish at a race in New Hampshire.

Gobert was second in points in the AMA Superbike standings and was scheduled to compete in a 100-kilometer event Sunday at the Mid-Ohio Sports Car Course. He has won three races this season and was two points behind two-time defending series champion Doug Chandler in the Superbike standings.

Gobert has been nicknamed "Wild Child" because, much like the Chicago Bulls’ Dennis Rodman, he regularly changes his hair color. He showed up at Mid-Ohio with pink hair and also has competed with hair dyed fuchsia, fire-engine red, blond, black and a combination of black and blond.

"I was wrong. Just plain wrong," Gobert said following the Laguna Seca event. "I did have a bit of smoke after Loudon (site of the New Hampshire race), in celebration, which I didn’t realize would be considered a serious problem. ...

"I hope everyone will chalk this up to a true mistake in judgment, and give me another chance to bring home a championship."