Dortmund, Germany (SportsNetwork.com) - Borussia Dortmund midfielder Sebastian Kehl is set to miss the next month because of a shoulder injury.

Kehl suffered the problem in Dortmund's 1-0 friendly win over Steaua Bucharest over the weekend, and tests have confirmed that he will need around four weeks to recover before returning to action.

The 34-year-old started 13 of Dortmund's 17 games in the Bundesliga in the first half of the season, and his absence will come as a blow to manager Jurgen Klopp as he attempts to drag Dortmund away from the relegation zone.

Dortmund is currently second from the bottom having won just two of their last 14 games in league play, and the club sits above last-place Freiburg on goals scored.

The club resumes its league campaign on Jan. 31 with a trip to third-place Bayer Leverkusen.