One out later, Davis sent a shot into the right-center field gap, plating two runs to put the Mets ahead for good and helping to snap a three-game New York losing streak.
Jose Reyes added a two-run double and Chris Capuano (1-0) earned the victory with six innings of four-run ball, allowing seven hits with a walk and striking out eight.
The Nationals got a three-run homer from Danny Espinosa and Ian Desmond added a solo shot.
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