Garnett, 36, has played a total of 46 minutes in the first three preseason games and Rivers could give him a break before Tuesday's game with Brooklyn Nets.
"We play (a) back-to-back and I want him playing (tomorrow)," Rivers said.
RIvers said he was unsure what to take out of Saturday's 98-95 overtime loss to the New York Knicks but he wasn't thrilled to play overtime.
"I keep getting asked that question, I don't know what I am supposed to take," he said. "I kinda just watch the game and we're improving in some areas. Our weak side defense wasn't very good so we have to improve in that area. That's all I'm looking for right now."
Also, Rivers said he has no update on Chris Wilcox, who made the trip to Philadelphia but is out indefinitely with back issues. Asked if Wilcox's absence hurt the club, Rivers said:"That doesn't do a lot. We would love to have him. We would love to have an extra body but the other bigs are playing great."