Borussia Monchengladbach midfielder Fabian Johnson will be out "until further notice" with an Achilles problem, according to the club.
Johnson, who turned 29 on Sunday, missed his club's Bundesliga match against Mainz on his birthday. Monchengladbach won the game 1-0 — its first win in eight league matches.
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The U.S. international has made 20 appearances in all competitions for Gladbach this season, scoring two goals and adding two assists.
Borussia Monchengladbach is currently in 12th place in the Bundesliga, and will take part in the Europa League later this season after finishing third in a Champions League group that included Barcelona, Manchester City and Celtic.