Per Mertesacker has been backed to prove a success at Arsenal by former club Werder Bremen.
The experienced Germany centre-back moved to Emirates Stadium on transfer deadline day for an undisclosed fee after several years of speculation.
It has been suggested Mertesacker could struggle to adapt to the pace and power of the Premier League.
But Bremen general manager Klaus Allofs told Kreiszeitung Syke: "Per Mertesacker always said he would have loved to remain with us. I trust him, he is simply an absolute honest character.
"But he also said he would love to join Arsenal now. This is why we then started to negotiate a deal.
"We were not taken by complete surprise as you could foresee such a bid. We agreed with Arsenal FC on Tuesday, these negotiations went quickly. We are delighted with the deal."
Allofs added: "I believe Per Mertesacker is a good fit, he will do well in the Premiership. He will break through. It's obvious his game needs a bit of adopting to that standard there. But he is an intelligent player, he will do so."
Bremen on deadline day also confirmed the signing of Germany youth international Florian Hartherz from Wolfsburg on a three-year contract.