Bass suffered a bruised right knee during the first half and did not return. His injury isn't believed to be serious, and he is expected to play Saturday against the New York Knicks. He sat out more than two weeks (and six total games) last February while battling right knee inflammation.
"Knee again," Rivers said after the game. "I don't know if it's bad, but we just didn't take any chances."
Pierce twisted his left ankle after landing awkwardly on Gerald Wallace's foot after a made 3-pointer midway through the second quarter. He went to the locker room to get retaped and returned for the second half.
"Paul tweaked his ankle, or he thought we were going to practice (on Friday)," Rivers said jokingly. "It's one of the two. I'm not sure yet. We'll find out. I think he tweaked his ankle, but I am suspicious."
The Celtics will take Friday off while bussing from Brooklyn, N.Y., to Albany, N.Y., where they meet the Knicks on Saturday night. Rivers hinted that veterans such as Pierce will have a light workload on the first night of a back-to-back to wrap up preseason play.
"This was the hardest game that (the veterans will) play, I can tell you that," Rivers said. "Maybe the last game (against Philadelphia on Sunday) they may play one good half. The New York game, I would be surprised -- we've got to play somebody. But a lot of them are not playing. They already know that. They knew that before this game. And then we get seven days (of practice) to work and prepare for the start of the season (after Sunday's game)."