She became the oldest player in WNBA history at 39 while playing for the Phoenix Mercury in 1997, the league's inaugural season.
Shock coach Bill Laimbeer says Lieberman, an ESPN analyst, was impressive during drills during last year's WNBA All-Star game.
A spot opened up for Lieberman when standout forward Cheryl Ford suffered a season-ending knee injury Tuesday night when the Shock, assistant coach Rick Mahorn and the Los Angeles Sparks were involved in a skirmish.
Lieberman will be active for Thursday night's game in Houston.
