The Pittsburgh Steelers solidified one of their problem areas of 2007, signing center Justin Hartwig to a two-year, $4-million contract.
The deal includes a $975,000 signing bonus.
Hartwig, who was released by Carolina last week in a salary cap-related move, will be expected to compete with 2007 starter Sean Mahan and second-year pro Darnell Stapleton for the center position in 2008.
Mahan was a disappointment to the Steelers last season after joining the team as a free agent from Tampa Bay as a replacement for Hartings, who retired.
The 6-4, 312-pound Hartwig is entering his seventh NFL season after joining the league as a sixth-round draft pick of the Tennessee Titans in 2002.
He was a three-year starter at center for the Titans before Carolina signed him to a 5-year, $17-million contract in 2006. Hartwig, however, was limited to two games that season after being placed on injured reserve with a groin injury.
Hartwig made 15 starts for the Panthers in 2007 before ending the season with a knee injury. He has appeared in 67 career games, starting 63 of them, all at center.
The Steelers have lost one free agent, guard Alan Faneca.