"I have known him for a lot of years," Sokratis said of his new team-mate.
"He also speaks some Greek and is a very good guy. I am happy also that we took a player like him, with experience.
"When I was in Dortmund I played with Hummels, who has the same style as David. It was also a very good partnership and it is very good (now with Luiz).
"It was his first game, it is important that we won and we can go from here."