Hannover have completed the signing of Karim Haggui on a two-year contract from Bayer Leverkusen.
The Tunisian defender's contract with Leverkusen had expired following the end of the season and Hannover have moved quickly to secure his services.
Dieter Hecking's side conceded 69 goals, the most in the Bundesliga, during the 2008/9 campaign as they finished 11th in the table.
And general manager Jorg Schmadtke is delighted to have captured the 25-year-old so early in the summer.
"Karim is a young lad, however he has picked up a lot of experience in the game," Schmadtke told the club's official website.
"He is a fully dedicated defender and will certainly be of help for our club."
Hecking added: "He will make our defence more stable."
The recruitment of Haggui could bring Hannover's pursuit of Middlesbrough centre-back Robert Huth to an end.
Schmadtke announced on Monday that the German was a potential transfer target.