The German Soccer Federation (DFB) said on Saturday it would investigate possible anti-doping rule violations by Hoffenheim players Andreas Ibertsberger and Christoph Janker during a test in early February.

In a statement the DFB said both players had tested negative at the time but their delay to appear for the doping test immediately after the match against Dortmund on Feb. 7 could have repercussions.

"Selected for a doping control, the two players failed to go directly to the doping control room immediately after the final whistle," the DFB said. "Instead they appeared there after attending a team meeting with a 10-minute delay."