Germany Under-21 international Johannes Geis has completed his move to Schalke 04.
The midfielder, who has arrived at the Veltins-Arena for an undisclosed fee, had spent the previous two years playing for Mainz 05.
"Schalke fascinates me. The stadium, the fans - playing in the Arena is something special. I want to roll up my sleeves and work hard," the 21-year-old told the club's official website.
Sporting director Horst Heldt added: "We are delighted that one of the most coveted young players has chosen to join our club. Johannes possesses many great qualities."
To date, Geis, who has signed a four-year contract, has made a total of 75 Bundesliga appearances.