Celtic have signed the Germany Under-21 midfielder Mika Baur from Paderborn on an initial four-year contract, with the option of a further year. It is their fourth signing of the summer, following Camilo Duran, Kasper Høgh and Haissem Hassan.
The fee is understood to be around £6.8m, made up of an initial £4.5m with a further £2.3m in add-ons, a large proportion of which is tied to Celtic reaching the league phase of the Champions League, as with the deals for Duran, Høgh and Hassan.
Baur, 22, joins after helping Paderborn end a six-year absence from the Bundesliga, finishing third in the second tier last season before beating Wolfsburg in the promotion play-off. He made 36 appearances in total, scoring four goals and providing six assists, and was named the club's player of the year.
Baur said the move felt right from the start. "It's absolutely the right move. It's a great club and I've heard incredible things about the fans," he said. "I'm in the same agency as Nicolas Kuhn so I called him to ask a couple of questions and he was so positive. He said, if you have the chance, just do it. I've had a good pre-season with good matches and tough training sessions, everything. So I'm in good shape and I'm ready to go."