Borussia Dortmund have reacted to their long list of injuries ahead of Saturday's Bundesliga showdown with Bayern Munich by signing ex-Germany defender Manuel Friedrich until the end of the season.
Second-placed Dortmund host Bundesliga leaders Bayern with Pep Guardiola's European champions four-points clear at the top.
Borussia were dealt a double injury blow on Wednesday when scans revealed both centre-back Mats Hummels and left-back Marcel Schmelzer returned with injuries from international duty with Germany.
Torn ankle ligaments will keep Hummels out until mid January, while a torn calf muscle means a three-week lay-off for Schmelzer.
With centre-back Neven Subotic out for six months with torn ligaments and right-back Lukasz Piszczek only just back in training from surgery, Dortmund will face the league leaders without their entire first-choice back four.
Having been released by Bayer Leverkusen at the end of last season, centre-back Friedrich, 34, was previously without a club and made the last of his nine appearances for Germany in February 2008.
"We have reacted to the injuries in our defence. Manuel Friedrich has extensive experience and has made a good impression in training," said Dortmund's director of sport Michael Zorc with Friedrich having signed a contract until June 2014.
Friedrich is set to partner Greece international Sokratis Papastathopoulos at centre-back against Bayern and has also played for Werder Bremen and Mainz in his Bundesliga career, making 247 league appearances and scoring 15 goals.
"I am thrilled to be allowed to run out in the Borussia Dortmund jersey," said Friedrich, who had been training with third division Rot-Weiss Oberhausen to stay fit.
"Until now, I had only done that as a guest in Dortmund and when the famous "Yellow Wall" (of Borussia fans) was against, not supporting you.
"I'm looking forward to a cool time in the black and yellow jersey."