Portugal Colonial - Wirtz stretchered off as Leverkusen lose home derby to Cologne

Wirtz, 18, twisted his knee in a first-half challenge and the attacking midfielder was carried off in clear distress.

His injury makes him doubtful for Germany's friendlies at home to Israel on March 26 and the Netherlands away three days later.

Wirtz's injury capped a bad day for Leverkusen as Cologne replacement Kingsley Schindler came off the bench to score the visitors' second-half winner with his first Bundesliga goal.

The loss of Wirtz could be a serious blow to Leverkusen with their top-scoring Czech striker Patrik Schick already sidelined by a torn calf.

Despite defeat in the home derby, Leverkusen remain third in Germany's top flight.

They are 15 points behind league leaders Bayern Munich who were held to a 1-1 draw at Hoffenheim on Saturday.

This is Leverkusen's second straight defeat after losing to Atalanta in their Europa League last 16, first-leg tie on Thursday.

Cologne are seventh in the league table as Steffen Baumgart's visitors' out-thought and out-muscled Leverkusen.

The hosts lost two key players in the opening half an hour of the bruising derby.

Leverkusen's Dutch defender Jeremie Frimpong had to be helped off with a suspected knee injury after a crunching tackle before Wirtz left on a stretcher.

G.Teles--PC