After Rick Ankiel led off the sixth with a single to left, Ramos ripped a 1-1 Tommy Hanson pitch into the left-field stands for his ninth homer, expanding a 3-2 Washington lead.
Ramos had earlier doubled in a run in the second, starting a three-run rally that included a two-RBI single by pitcher John Lannan.
Lannan has just been removed from the game in favor of Ryan Matttheus with runners on first and second. The lefty worked 5 2/3 innings, allowing five hits. He walked four and struck out four.