Moreno scored in the 35th, 29th and 43rd minutes, pushing his season total to five and giving the Galaxy (4-1-3) a 3-0 lead. All three goals were assisted by Andreas Herzog.
Moreno turned playmaker as he had one of the assists on Joseph Ngwenya's first goal of the season that gave Los Angeles a 4-0 lead in the 44th minute before Washington (2-3-3) began a comeback.
In extra time before intermission, Ronald Cerritos scored his second goal of the season. Freddy Adu, who came on as a substitute for Cerritos in the 60th minute, struck seven minutes later with an unassisted tally, his second of the season.