Celtic have completed the signing of Sweden international defender Mikael Lustig on a free transfer after passing a medical.
The 25-year-old agreed a pre-contract in November and the Bhoys have finalised the deal ahead of the transfer window opening on Sunday.
Lustig, who can operate at right-back or in central defence, has signed a three-and-a-half-year contract at Parkhead.
The former Rosenborg defender watched Wednesday's 1-0 win over Rangers and could make his debut on Monday against Dunfermline.
"Celtic Football Club are delighted to confirm that new Bhoy Mikael Lustig has passed his medical and confirmed his new deal," read a statement on the club's official website.
"The Swedish international, who signed a pre-contract earlier in the season, has been in Glasgow over the past few days to take in the derby victory and finalise his new contract - which will officially start on January 1, 2012.
"Mikael will be officially unveiled as a Celt at a media conference at Lennoxtown (on Friday)."