Leeds defender Robin Koch will undergo knee surgery after aggravating an existing injury in Saturday's Premier League defeat to Chelsea.
The 24-year-old initially sustained the injury on his debut in the opening game of the season against Liverpool.
But after playing through a hectic spell of 10 games plus an international break with Germany, Koch suffered further damage against the Blues.
Koch was due to undergo an operation in London on Tuesday after the club determined that "surgery is required to remedy the problem".
It is another blow for Leeds boss Marcelo Bielsa, who is faced with having only two fit senior centre-backs in his squad.
Diego Llorente and Liam Cooper are Bielsa's current remaining options with no indication as yet of how long Koch will be sidelined.
