Cologne have signed Germany under-21 international Dominique Heintz from second-tier club Kaiserslautern.
The 21-year-old is set to replace Tottenham signing Kevin Wimmer in the club's back four.
The Bundesliga club announced that Heintz has signed a three-year-deal with Cologne, who earlier this summer sold Austria international Wimmer to Spurs.
"We are convinced that we can together make the next steps in his development," the club's sporting executive Jorg Schmadtke said of the 21-year-old left-footed centre-back, who came through the ranks of the Kaiserslautern youth academy.
Heintz currently is with the Germany under-21s as they prepare for the European Championships in the Czech Republic later this month.
"I wanted to become a Bundesliga player, and in Cologne have found the right club for this step," Heintz said. "They are a traditional club with outstanding fans.
"Most of all the club board and the coaching staff convinced me with their concept of banking on young players and advancing them."
Cologne reportedly splashed out some €1.5 million on Heintze, who has made one first league appearance and featured in a further 63 second-division games, but he missed major parts of the last season following a muscle tear suffered in February.