With free agency set to start at 4 p.m. on Tuesday, the Falcons on Monday retained the services of offensive lineman Mike Johnson, reaching a one-year contract extension with the three-year veteran.

Teams may keep negotiating with their own players up to the deadline in order to keep them from reaching the open market.

Johnson, after a productive 2012 season as the jumbo tight end, was set to take over at right tackle last season before he suffered a dislocated left ankle and fractured fibula during a preseason practice with Cincinnati.

The injury required surgery and he was placed on injured reserve.

Johnson had played all 16 games in 2012, making one start. The Falcons were hopeful that he would be an athletic upgrade over veteran Tyson Clabo, who was released last offseason.

Johnson was highly touted coming out of the SEC and Alabama, where he played on the 2009 national championship team. Falcons defensive tackle Corey Peters said that Johnson was the toughest player he faced while playing for Kentucky.

A four-year starter at Alabama, Johnson was a third-round pick (98th overall) in the 2010 NFL draft.

The Falcons, who have elected not to use the franchise or transition tag this offseason, have now signed Johnson and Peters to one-year extensions.

The Falcons’ list of potential unrestricted free agents includes defensive tackle/end Jonathan Babineaux, center/guard Joe Hawley, defensive tackle Peria Jerry, tackle Sean Locklear, tackle Jeremy Trueblood, tight end Chase Coffman, cornerback Dominique Franks and linebacker Omar Gaither.