PRAGUE, Czech Republic -- Czech tennis player Bohdan Ulihrach tested positive for the banned steroid nandrolone during an ATP Tour event in Moscow in October.

Ulihrach issued a statement announcing the result and adding: "I can't explain how the banned substances could get into my body.''

The positive result came on the "A sample'' of the test. He won't be punished unless a second -- or "B sample'' -- also turns up positive. Ulihrach, who would be subject to a two-year ban in that case, said he expects to learn the results of the "B sample'' in the next few days.

He said he passed a drug test in New York on Aug. 28, and in Vienna on Oct. 11, a week after the positive test.

Czech tennis officials refused to comment Thursday.

The 27-year-old Ulihrach has won three ATP Tour singles titles, and his highest ranking was 22nd in 1997. He's never been past the fourth round at a Grand Slam tournament and lost in the first round at all four majors last year.

Ulihrach said he was injured in December and that's why he won't play for the Czech Republic in next week's first-round Davis Cup match against Russia.