Jermaine O'Neal

The Celtics don’t know how long Jermaine O’Neal will be out with his knee injury, but it will be measured in weeks, not days. “Two, three weeks would be a guestimate,” Doc Rivers said Monday. “We don’t know exactly. We’re going through a couple of more evaluations.”

O’Neal sought a second opinion in Miami on his injured left knee and didn’t travel with the team to Memphis for the last game on their road trip. Rivers said he hasn’t “heard the word ‘surgery,’” yet, but there’s still no real timetable on O’Neal’s return.

Shaquille O’Neal returned to the Celtics lineup and for now he and Semih Erden are playing 30-32 minutes a night in the post, while Glen Davis takes up the rest of the minutes. It’s not perfect, but the Celtics are hanging on for now with the arrangement.

“Semih and Shaq are playing through whatever they’re playing through,” Rivers said. “Semih’s shoulder and Shaq’s everything, really. It’s a concern but there’s nothing we can do about it. We’re not going to go out and get anyone else. There are not a lot of really good 7-footers walking the earth that are not signed in the NBA, so we just have to make do.”

The Celtics may also be without Marquis Daniels who missed practice and isn’t expected back Tuesday with what Rivers called a family issue. There is some doubt as to whether Daniels will be with the team Wednesday when they play the Wizards.