Poland goalkeeper Lukasz Fabianski has joined Arsenal from Legia Warsaw.
Fabianski is a Polish international
The 22-year-old signed from Legia Warsaw on a "long-term" contract for an undisclosed fee.
Fabianski has made four appearances for his country and was voted the Polish league's best goalkeeper in each of the last two seasons.
The understudy to Celtic's Artur Boruc in the national team will join Jens Lehmann and Manuel Almunia in Arsenal's keeper ranks.
Arsenal boss Arsene Wenger told the club's official website: "We are pleased to have signed Lukasz Fabianski.
"He is a very good young goalkeeper who will provide good support to our squad.
"He has performed consistently well for Legia Warsaw in recent seasons and was rightfully rewarded with a place in the Polish World Cup squad.
"Lukasz will be a big asset to our squad and we are looking forward to him joining us for pre-season."
Fabianski said: "I am delighted to be joining Arsenal. They are a great club with many world-class players and I am really looking forward to meeting my new team-mates.
"Arsenal is one of the biggest and best clubs in Europe and I hope that I can help the team win trophies in the future."