Nikolas Nartey missed VfB Stuttgart's game against Freiburg due to problems in the adductor area.
The Breisgauer won on 11th February without their coach Christian Streich, who was suspended, against VfB Stuttgart 2-1, Grifo turned the heated Baden-Württemberg derby almost single-handedly with two converted penalty kicks.
The Italian national player Grifo kept his nerve with both penalties (60th/84th minute), which were only given after a long view of the VAR. Chris Führich in the 30th minute scored the consolation goal for the visitors.
During the training session on Sunday, the central midfielder, who was also last used as a full-back, was able to work individually with the ball again. The rest of the week will show whether he will be there against Cologne on Saturday afternoon.
Nikolas Nartey has made six appearances in the German Bundesliga this season.