Jordan Farmar has torn his left hamstring for a second time this season, an ultrasound revealed on Wednesday.
The 6-foot-2 point guard will be out a minimum of four weeks.
He reinjured the same hamstring on Tuesday night in a loss to the Milwaukee Bucks, although, according to the Lakers, the tear is in a different location.
Farmar said he felt a "tug" in the hamstring against the Bucks (7-24), but was hoping it was just scar tissue. He left in the third quarter and didn't return as the Lakers fell to the team with the worst record in the NBA.
The Lakers (13-19) are also without point guards Steve Blake (elbow) and Steve Nash (back). Guard Kobe Bryant and forward Xavier Henry, who have played the point this season, are both out with knee injuries.
Recent signee Kendall Marshall, who has been with the team less than two weeks, will likely start at point guard.
The Lakers won't be able to add a player without opening a roster spot, already at the league maximum of 15.