Arsenal have completed the signing of Brazilian defender Gabriel Magalhaes from Lille for 26m euros (£23.14m).
The 22-year-old was a regular for the French side as they finished fourth in Ligue 1 last season and played in all six of their Champions League games.
He joins the Gunners on a long-term contract.
“He is a player we have been studying for a while and he was in demand from many clubs,” said Arsenal technical director Edu.
“Gabriel is a player of high quality and Mikel (Arteta) and his coaches are looking forward to integrating him into the club.”
Arsenal boss Mikel Arteta said: “We welcome Gabriel to Arsenal. He has many qualities which will make us stronger as a defensive unit and as a team.
“He has proved with Lille he is a defender with many outstanding attributes and we are looking forward to watching him grow as an Arsenal player.”