Manchester United have signed Vitesse Arnhem left-back Alexander Buttner for an undisclosed fee.
Buttner, 23, agreed to join Premier League newboys Southampton a month ago but the deal hit a snag due to a contractual dispute between the player and his club.
United's interest came out of the blue, after the Red Devils had been linked with Everton defender Leighton Baines for most of the transfer window.
The Ajax academy product, who was not capped by Netherlands at youth level beyond Under-20 and has not played for the senior side, has signed a five-year contract at Old Trafford.
Sir Alex Ferguson told the club's official website: "Alexander is one of the best young left-backs in Europe and we're delighted to sign him. He's someone we've been watching for a while now. He gives us some really exciting options in that position."
The player added: "Joining Manchester United is one of the best days of my life. It's a team I have admired for many years now and I can't wait to join my team-mates and play my part in helping the club be successful."