"I am playing tonight. Yes, I am," Rivers said.
The Celtics' "Big Three" was reduced to one Friday night against Toronto -- forward Ray Allen. Their usual starters were down by three -- with Paul Pierce, Kevin Garnett and Rajon Rondo all sidelined.
Boston opened with two of its usual starters -- Allen and center Kendrick Perkins. J.R. Giddens made his first professional start at guard. Rasheed Wallace was the other forward and Tony Allen stepped in for Rondo at point guard.
When asked if there was any timeframe for his starters to return, Rivers said: "Rondo and Paul are first in line."
Pierce, who spoke with the media in the dressing room before the game, plans on returning to practice Monday. He has been sidelined since undergoing two minor procedures for an infection in his right knee -- one on Dec 23rd, the other on Christmas night.
"As long as the swelling continues to go down," said Pierce, whose knee was wrapped. "It goes down every day. It seems like every day there's some improvement. I don't want to go out and hobble around and try and force it. I want to get back when I'm ready."
Pierce said he's been riding a bike to continue his conditioning. It'll be his fifth game out of the lineup.
Rivers wasn't sure when Pierce will be able to play.
"Like I've said earlier with infections, we don't know how to treat that [timeframe]," he said. "We've never had that. Paul's 50-50 to practice on Monday."
Rivers also it's likely going to be "around 10 days" before Garnett -- sidelined with a sore right knee -- resumes practicing. It was Garnett's second straight game on the sidelines.
Last season, Garnett played in just four games in the final two months of the regular season and missed all of the playoffs.
Rondo was out with a sore left hamstring.
One bit of good news for the Celtics was that Glen Davis, listed as day-to-day with a sprained right ankle, was expected to play.
"I'm not worried about his ankle," Rivers said. "It's his conditioning."
Davis returned on Christmas Day at Orlando after missing the first 27 games following right thumb surgery.