Atletico Madrid have signed Martin Demichelis on a free transfer after his contract at Malaga expired.
Demichelis, 32, said he was "very proud" to have joined the club, where he will be competing for a place in the defence that conceded the fewest goals in La Liga last season.
The Argentina international, whose club career included spells at River Plate and Bayern Munich, told reporters he was pleased to be moving to "such a successful and winning group".
He told reporters: "Next year, the team will compete even more than last season, and there are many challenges to face.
"I know that I'm joining the best defence in the league, and I hope we can keep that up. I will come here with a humble attitude, and will contribute what I can.
"I hope it's a successful year for me and for the team."
Demichelis, who turned down the offer of a contract extension at Malaga and had also been linked with a return to River Plate, his boyhood club, said coach Diego Simeone had been a key factor in him opting for Atletico - echoing the thoughts of fellow newcomer David Villa.
"It was a difficult decision because two clubs to which I am eternally grateful, River and Malaga, wanted to sign me," he explained.
"But then Atletico appeared, and Simeone was key in convincing me to join a consolidated group that was playing for trophies.
"Simeone has known about me for a long time, and is aware of my performances in the last few years. He is one of the main reasons I'm now an Atletico player."
Information from the Press Association was used in this report