Schalke have announced the signing of midfielder Johannes Geis from Mainz.
Geis, who had been linked with Borussia Dortmund, has signed a four-year contract with Schalke, for a reported fee of €10 million plus bonuses.
Schalke's sporting director Horst Held told the club's official website: "We are very happy that one of the most sought-after young players has decided to join our club."
Heldt praised the "enormous qualities" of the 21-year-old, adding: "His dangerous set-pieces, his precise passing game and his eye for unmarked teammates make him one of Bundesliga's best central midfielders.
"That he has led Mainz onto the pitch as skipper at such a young age shows that he is capable to take on responsibility."
Geis is currently in the Czech Republic representing Germany at the European Under-21 Championship and is facing the hosts in a decisive group match on Tuesday night.
He said about his transfer: "Schalke fascinated me, the stadium, the fans: It is something special to play in this arena. I want to roll up my sleeves and step on the gas there."
- FC Schalke 04 (@s04_en) June 23, 2015
Geis, who joined Mainz from SpVgg Greuther Furth in 2013, added that the talks with Heldt and coach Andre Breitenreiter convinced him to join Schalke.
He said: "Something new can develop at Schalke and I want to be part of that."
Geis played in all 34 Bundesliga matches last season, scoring four goals and providing another four assists.