NEWARK - Mickael Pietrus is slowly working back into basketball shape while recovering from a concussion, all amid a busy portion of the Celtics’ already difficult schedule.

Saturday night against the Nets was the guard’s third game after missing nearly three weeks following a frightening fall March 23 against the 76ers. In the first two games (against Atlanta and Toronto), he had a total of 11 points on 4-for-12 shooting and logged 53 minutes, mostly because of the ankle injury to Ray Allen.

“I’m not close to where I was,’’ he said before scoring 5 points in the Celtics’ 94-82 win. “When you’re dealing with a concussion, you have to experience a couple of things before you get back to where you came from. At the same time, just trying to get through a rhythm so I can help the team in the playoffs because I know that right now a lot of games are going to come for us and it’s very important.’’

Pietrus was a key bench player before his injury and coach Doc Rivers was forced to throw him back into the rotation with heavy minutes because of a lack of depth. So Pietrus is using games to get into shape.

“I haven’t played for three weeks, so I have to put more minutes and more games under my legs so in the playoffs I won’t have any problems,’’ he said. “At the same time, you can always get your rhythm, not offensively but defensively.’’

Pietrus laughed when asked if had ever played three games in three nights - the Celtics play Sunday in Charlotte.

“Yes in Europe,’’ he said. “Sometimes we played four games in a row. I think the NBA got that from us. You just have to enjoy it.’’

Pierce injures toe

Paul Pierce jammed his left big toe in the fourth quarter and his status for Sunday’s game against the Bobcats is uncertain. Pierce said he discussed the possibility of taking a game off before the playoffs with Rivers and the Charlotte game may serve as an opportunity.

Green growth