LAFC needed a late Latif Blessing goal to escape a scare from USL side Sacramento Republic and advance to the U.S. Open Cup quarterfinals on Wednesday night.
The quarterfinals took shape as USL club Louisville City and MLS' Orlando City and Chicago Fire also advanced, to join the Philadelphia Union, Houston Dynamo, Sporting Kansas City and the Portland Timbers.
Sacramento, spurned in the latest round of MLS expansion, took the lead twice only to be pegged back by LAFC goals from Benny Feilhaber and Diego Rossi, before Rossi delivered the winner in the 89th minute.
Louisville City is the last lower-division club left in the competition after they defeated Nashville SC 2-1.
The defending USL champions took the lead in the first half through Paco Craig, then Paolo DelPiccolo doubled the lead, ensuring Matt LaGrassa's second-half header wasn't enough for the visitors.
Louisville will next travel to face the Chicago Fire, who ousted Atlanta United 1-0 in front of a U.S. Open Cup-record crowd of 41,012 at Mercedes-Benz Stadium.
Nemanja Nikolic's 54th-minute goal on the counter-attack was enough for the Fire to move on.
Orlando City scraped past D.C. United in a shootout at the Maryland SoccerPlex after the game ended 1-1.
D.C. United took an early lead through Luciano Acosta but Orlando, playing in the first game since sacking Jason Kreis last week, equalized soon after through Justin Meram.
Chris Durkin was sent off with a second yellow card in extra time, but the game was decided from the spot, after Acosta hit the crossbar while attempting a panenka.
U.S. Open Cup quarterfinals (all games July 18):
Orlando City at Philadelphia Union
Louisville City at Chicago Fire
Sporting Kansas City at Houston Dynamo
Portland Timbers at LAFC