The Galaxy are hoping both stars will be on the Home Depot Center field for the rematch Saturday night, though goalkeeper Donovan Ricketts will remain sidelined as his team tries to extend an 11-game unbeaten run.
Donovan was out with an inflamed right knee and Beckham was serving a suspension when the Galaxy won 2-1 at Chicago on April 17.
Donovan, whose eight goals are tied for second in MLS, admittedly wasn't sharp when he returned Monday in a scoreless draw with Seattle after missing four games because of the Gold Cup. Beckham, whose seven assists are tied for second most in the league, has a stress fracture in his spine but played 21 minutes, his first action in three games.
Although he's suffering from fatigue, Donovan is expected to play Saturday while Beckham is listed as questionable.
"We're probably better with them," coach Bruce Arena told the team's website. "It's not got to be something that happens overnight were we get them both back and we get them playing 90 minutes together."
Los Angeles has an MLS-best 36 points despite enduring a number of key absences this season. The club is now dealing with another one, as Ricketts is out of the lineup for three to five weeks.
The 2010 MLS goalkeeper of the year had surgery for a fractured left forearm sustained June 25.
In Ricketts' place, the Galaxy (9-2-9) got an admirable effort from Brian Perk in his league debut Monday as he stopped an early penalty kick. Perk might be on the sidelines for this game, though, with Josh Saunders eligible to return from a red-card suspension.
Whoever is in goal will try to help the Galaxy end the Fire's eight-game unbeaten streak, their longest since a 5-0-6 start to the 2009 season.
Chicago (2-4-12), though, has one win in that stretch and recorded its second straight 1-all draw last Saturday. Dominic Oduro scored in the 26th minute against Chivas USA, but the Fire allowed the equalizer just after halftime.
"We have to stay focused for 90 minutes," defender Cory Gibbs said. "We had lapses against Chivas. If we do that against a team like the Galaxy, we'll lose."
The Fire's defeat to Los Angeles in April was their third straight. They've gone 1-1-11 since.
Chicago has given up three goals in seven games since Frank Klopas took over as interim coach for the fired Carlos de los Cobos.
Donovan scored twice in Los Angeles' last home game against the Fire on Aug. 1, but Chicago had built a 3-0 lead in the first 19 minutes and hung on for the 3-2 victory.
Los Angeles hasn't gone unbeaten in 12 straight since a 10-0-2 start to last season.