Los Angeles Galaxy reached the Major League Soccer Western Conference final with a victory over local rivals Chivas USA.
The Galaxy progressed to Friday night's game against Houston Dynamo with a 1-0 second-leg win over Chivas at the Home Depot Centre courtesy of a 73rd-minute Landon Donovan penalty that gave them a 3-2 aggregate victory.
The win leaves the Galaxy just one game away from the MLS Cup final which decides the league champions, but next weekend's game against Houston in Los Angeles means Beckham will miss England's friendly against Brazil in Qatar on Saturday.
Beckham had sent in a defence-splitting pass to Donovan that led to Mike Magee being felled for the game-winning penalty kick, but the Englishman was forced out of the action five minutes later having struggled from a knock to his lower back.
The England international had ice strapped to the problem area and watched from the bench as as his team-mates hung on to their lead against a late Chivas rally.
Houston had reached the conference final earlier in the day with a 1-0 home win over Freddie Ljungberg's Seattle Sounders. Brian Ching's stoppage-time winner had been the only game of the two-legged tie and brought to an end a successful inaugural season for the Sounders.
In the Eastern Conference, the Chicago Fire progressed at the expense of the New England England Revolution and will face Real Salt Lake, who knocked out defending MLS champions Columbus Crew on Friday.