Rivers, 25, is averaging a career high 15.8 points this season for the Clippers.
"It's not the best news, obviously. He'll be evaluated in two weeks which doesn't sound great right now, so we'll find out a lot more in a couple weeks," Clippers coach Doc Rivers said before Thursday's game. "But listen, this is what we've been dealing with all year, so someone else will step up for us because they have to. That's what we've been doing and that's what we'll try again."
The team also lost Milos Teodosic after he aggravated a left foot injury in the game that had previously sidelined him two months. The team said Teodosic is day-to-day.
The Clippers have been plagued by injuries this season. Patrick Beverley is out for the rest of the campaign following surgery in November to repair a torn meniscus in his right knee. Danilo Gallinari is dealing with a partial tear in his left glute and will be re-evaluated later this month. Blake Griffin missed 14 games with a left knee injury.
DeAndre Jordan has been the only player on the team to appear in every game this season.
"It's been a long time. It's been a while," Rivers said when asked when was the last time he had a fully healthy squad. "This year's been just crazy. We've had one guy out before, but this year is just, I don't think I've ever seen anything quite like this. Not only are there a lot of injuries but they're to all the skill guys -- the scorers, the playmakers.
"When you think about it, it's just been one of those years. I love this team, I will say that. They obviously understand that we have all these injuries but they just, I don't know, it's a great group to coach. They just play hard."
ESPN's Royce Young contributed to this report.