Cologne says Germany international Lukas Podolski has been ruled out for three to four weeks after suffering a recurrence of a foot injury.
The Bundesliga side says Podolski partially tore a tendon in his left foot during Saturday's 4-1 league defeat at home to Schalke. The 26-year-old forward has previously had problems with the same injury.
Cologne says Podolski will need to give the foot a week's rest before starting rehabilitation.
Podolski is enjoying his best ever season, scoring again on Saturday to bring his season tally to 15 of Cologne's 28 league goals.
Cologne coach Stale Solbakken said, "we'll miss Lukas for a long time. It's the old injury again. Now we'll have to be more careful with it."