With a notoriously depleted front court that's forced Kevin Garnett to man the center position, the Celtics are close to signing free agent center Sean Williams, according to ESPN.com's Marc Stein. To make room, Boston will waive Jermaine O'Neal.
After playing eight games with Dallas earlier this season, Williams was waived by the Mavericks on March 22. The timing fortuitously came just one day before the league's deadline to give Williams eligibility to play beyond the regular season and into the playoffs for the Celtics.
With the foul prone Greg Stiemsma serving as Garnett's backup, and the recently signed Ryan Hollins filling in as the team's emergency big man, the signing of Williams gives Boston an athletic 25-year-old center to help in case the team suffers yet another injury during the postseason.