While the team said he will be evaluated in Monday in Los Angeles and a timetable for his return established then, sources said that he likely will be out four to six weeks.
Rivers suffered the injury moments before he was ejected for arguing with officials Wednesday in the Clippers' loss to the Minnesota Timberwolves. Initial X-rays came back negative, and Rivers told reporters he believed he had a bone bruise.
He missed Friday's victory in Orlando, and and MRI revealed the break.
It's another blow and another broken hand for the Clippers. Forward Blake Griffin suffered a broken hand two weeks ago, after a fight with a team staff member. Griffin, who has needed two surgeries on his hand, also is expected to be out four to six weeks.
Rivers has been having a good season for the Clippers and is averaging a career-high 8.1 points off the bench.