According to the Bundesliga club, Thomas Meunier, a fullback for Borussia Dortmund, has tested positive for COVID-19.
Before attending Dortmund's training camp in Switzerland, the 29-year-old defender took two tests and another before departing Bad Ragaz. All of the tests came out negative.
The Belgian international tested positive before the start of this week after having some time off and since then has been self-isolating.
Meunier made 33 appearances for the Black and Yellows last season, scoring once and assisting twice.