Schalke 04 must cope without defender Atsuto Uchida and midfielder Marco Hoeger after they were injured in the 2-2 Champions League comeback draw against Arsenal on Tuesday, the Bundesliga club said on Wednesday.
Uchida tore a thigh muscle in the 25th minute and was replaced by substitute Hoeger, who sustained a ligament injury midway through the second half and was taken off.
"The pair will be out for the coming weeks," said Schalke in a statement.
Schalke top Champions League Group B with eight points, one ahead of Arsenal with Olympiakos Piraeus on six after beating Montpellier HSC 3-1.
They are also second in the Bundesliga, seven points behind leaders Bayern Munich.