Lyon have announced the signing of Joachim Andersen, who joins the club from Sampdoria.
Andersen was unveiled at a news conference, where Lyon president Jean-Michel Aulas revealed the fee could reach up to €30million.
"It is with great pleasure that we welcome Joachim," Aulas said. "He was one of our recruitment priorities.
"We are very happy for his arrival and he has signed a five-year contract.
"The amount of the transfer is €24million with €6million bonuses, we want to go through a certain number of steps."
Andersen, 23, is yet to make a senior appearance for Denmark but has been capped at youth levels and included in full squads.
"It's a price between the two clubs, I just want to play and fulfil the ambitions of the club, it's the perfect environment to grow and grow," the defender said of his fee.
"I am very happy to be here at Lyon. I'm really looking forward to playing in my new colours. It's a fantastic club. I can't wait to see the city and the fans.
"I'm going to take a step back in my career here, it's a fantastic club, I wanted to play in the Champions League, I want to win titles too."