The German defender played the full 90 minutes of Liverpool's game with Sunderland on Saturday, while Carragher switched to left-back.
"All the players are delighted to see Markus back," said the Liverpool vice-captain. "I wouldn't wish what he has gone through on anyone.
"Markus did work in pre-season but the difference between friendly games and Premiership games is massive so the manager has done the right thing in bringing him back gradually.
"I am sure he is here to stay now."
