Cologne and Germany striker Lukas Podolski is expected to be out for up to four weeks after suffering a recurrence of a foot injury after scoring in his team's 4-1 Bundesliga defeat to Schalke.
The 26-year-old forward scored the opening goal on Saturday but then tore a ligament in his left foot. Podolski has previously had problems with the same injury.
Cologne said Podolski will need at least a week's rest before he starts rehabilitation work.
The injury is a blow to Cologne as the Germany star is currently enjoying his best-ever season having scored 15 of his club's 28 league goals this season, while his team are 13th in the league.
"We have no points (after two games) and now no Podolski, this is not a good Sunday," said Cologne coach Stale Solbakken.
"We'll miss Lukas, it's an old injury again.
"Now we'll have to be more careful with it and it means the other players will need to prove they can score goals."
Podolski now faces a race against time to be fit for Germany's friendly against France on February 29.