"For the second time in a week, Jermaine O'Neal's surgically repaired left knee swelled up, this time forcing the Celtics center to sit out last night's game against the Kings at TD Garden. It was the 21st missed game of the season for O'Neal, his first since returning to the lineup Christmas Day against the Magic.

After dealing with swelling during a loss in Dallas Nov. 8, O'Neal sat out for six weeks. In 10 games since returning to the lineup, and with little practice time, O'Neal had played well. But he had to leave last Friday's win over Raptors, calling it a "precautionary'' measure.

Coach Doc Rivers said he didn't know whether O'Neal would ultimately require surgery."