The home team put in a solid defensive shift, and a goal from each member of its forward tandem secured the win.
Matt Pickens had an excellent match in goal for the Rapids, who could easily have lost by several more goals were it not for his performance.
After an uneventful opening 25 minutes, D.C. United struck first when Lewis Neal found De Rosario with a perfect slotted pass, leaving the Canadian with a breakaway chance that he dispatched through Pickens.
The home side doubled the lead 15 minutes into the second half. Neal put in a cross and Branko Boskovic ghosted through the Rapids defense to head it, only for Pickens to make a great save. Hamdi Salihi, however, was unmarked and put home the rebound from close range.
The victory improved United's record to 6-4-3, which ties the team with Sporting KC for second place in the East on 21 points. Sporting does have three more games played.
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