"We don't have a timeline," said Galaxy spokesman Justin Pearson, who cast doubt on the centerback's availability for the October 25 match against Metapan in El Salvador. "Probably not, but he hasn't played the last two games in (the Champions League) anyway."
DeLaGarza injured the knee in a collision with Colorado Rapids forward Omar Cummings midway through the first half of Sunday's 1-1 draw at Dick's Sports Goods Park in the Denver suburb of Commerce City, Colorado.
He has started all 30 U.S. league matches for the Galaxy, which has the third-best record in Major League Soccer's Western Conference and sixth-best record overall.
The Galaxy already have clinched their place in the quarterfinals, having earned seven points from three games. The Puerto Rico Islanders are second with four points, but has completed their schedule, and Metapan is last with one point.
However, quarterfinal pairings will be determined by seed, which will be based on each qualifier's group record. The Galaxy have the fifth-best record heading into the final round of matches, and would play Herediano (which has the fourth-best record).