The Asian Football Confederation provisionally suspended Nagoya Grampus forward Jakub Swierczok on Friday for testing positive for a banned substance during the Asian Champions League.
The AFC said Swierczok's A sample came back positive for the as-yet unspecified substance following Nagoya's quarterfinal loss to South Korea's Pohang Steelers in Jeonju on Oct. 17.
The 28-year-old Poland international will be suspended from all soccer activities until the AFC completes an investigation.
Grampus said Friday they have requested further analysis of the B sample collected after the match, in line with anti-doping procedures.
The club said only a very small amount of the substance had been detected and the player had no recollection of ingesting anything prohibited.
Swierczok joined Grampus in July this year, midway through the J-League first-division season, going on to score seven goals in 14 J1 appearances.
He helped the club advance to the ACL quarterfinals with a hat-trick in their 4-2 win over South Korea's Daegu FC in the round of 16 in September.
