Washington Nationals' Ryan Zimmerman celebrates his two-run home run in the fifth inning against the San Francisco Giants on Wednesday, July 4, 2012, in Washington. The Nationals won 9-4. (AP Photo/Nick Wass)

Photo by: Nick Wass

Washington Nationals' Ryan Zimmerman celebrates his two-run home run in the fifth inning against the San Francisco Giants on Wednesday, July 4, 2012, in Washington. The Nationals won 9-4. (AP Photo/Nick Wass)