BOSTON (CBS) – Celtics reserve center Jermaine O’Neal underwent successful arthroscopic knee surgery on Friday, president of basketball operations Danny Ainge said after the Celtics 101-97 loss to the Dallas Mavericks.

A few weeks ago, O’Neal opted not to have surgery on his injured left knee instead hoping rehab would get him back on the court. O’Neal is expected to miss the next six to eight weeks.

That time frame would have him return sometime in April, and O’Neal said via his twitter account on Saturday he expects to be back for the playoffs.

“I know I haven’t been out there much this year, but I promise I will be there when the Cs need me the most! That I guarantee!” he tweeted.

He also tweeted about the surgery, saying it went well and was a much-needed procedure.

The Celtics made sure to have plenty of depth at the center position heading into the regular season. With Kendrick Perkins out the first three months while returning from ACL surgery, Boston signed Shaquille and Jermaine O’Neal to go along with rookie big-man Semih Erden. All four have started games for the Celtics at some point during the season.