The Lakers agreed to terms on a contract with free-agent power forward Josh McRoberts but lost power forward Derrick Caracter for an undetermined period because of torn cartilage in his left knee.
McRoberts, 24, averaged 7.4 points, 5.3 rebounds and 22.2 minutes a game last season for the Indiana Pacers, starting 51 of the 72 games in which he played. He is 6 feet 10, 240 pounds, and is beginning his fifth NBA season.
McRoberts might end up starting for the Lakers in their season opener because Lamar Odom was traded over the weekend and Andrew Bynum must serve a five-game suspension, meaning Pau Gasol would slide over to center for the first five games.
Luke Walton and Metta World Peace have been practicing at power forward in recent days.
Caracter was injured at practice Monday and will undergo surgery Wednesday morning, a team spokesman said. A timetable for his return has not been established, but it will be closer to two months than two weeks.