A conclusive diagnosis is not expected until Cousins undergoes additional tests in Los Angeles on Thursday.
The 29-year-old four-time All Star was working out in Las Vegas on Monday when he had to leave the court. One source said Cousins had "bumped knees" with another player.
Cousins has been prone to injury in the past. He tore his Achilles tendon while playing for the New Orleans Pelicans during the 2017-18 season and injured his quadriceps last season with the Golden State Warriors.