A Czech player has been suspended for two years by UEFA for testing positive for an undisclosed banned substance after a Champions League match in November.

Defender David Bystron of Czech champion Viktoria Plzen was informed on Thursday of the ban, which was backdated to Jan. 3.

Bystron tested positive after the Nov. 23 match at BATE Borisov in the Belarus capital Minsk. Plzen won 1-0, a victory that helped the team earn a spot in the Europa League for finishing third in its group behind Barcelona and AC Milan.

Plzen says it is up to Bystron to reveal the substance.

Plzen faces Germany's Schalke next week in the Europe League.