Midfielder Thomas Partey has joined Arsenal on a long-term contract from Atletico Madrid.
The 27-year-old scored four goals in 46 appearances as Atletico finished third in LaLiga and reached the UEFA Champions League quarter-finals last season.
Gunners manager Mikel Arteta said he is delighted to finally acquire his long-time target, who joins for an undisclosed fee.
“We have been watching Thomas for a while, so we’re now delighted to add such a high quality player to our squad," Arteta told the club's official website.
"He is a dynamic midfielder with great energy. He brings a lot of experience from a top club that have competed at the highest level in LaLiga and the Champions League for several years."
The Ghana international will wear the No 18 shirt.
Arsenal's next match is at Manchester City on Saturday 17 October.